netcdf-f77.md
The NetCDF Fortran 77 Interface Guide {#nc_f77_interface_guide}
=====================================
[TOC]
This document describes the FORTRAN-77 interface to the netCDF library.
1 Use of the NetCDF Library {#f77_Use_of_the_NetCDF_Library}
=============================
You can use the netCDF library without knowing about all of the netCDF
interface. If you are creating a netCDF dataset, only a handful of
routines are required to define the necessary dimensions, variables, and
attributes, and to write the data to the netCDF dataset. (Even less are
needed if you use the ncgen utility to create the dataset before running
a program using netCDF library calls to write data. See
section ‘ncgen’ in The NetCDF Users
Guide.) Similarly, if you are writing software to access data stored in
a particular netCDF object, only a smallbset of the netCDF library is
required to open the netCDF dataset and access the data. Authors of
generic applications that access arbitrary netCDF datasets need to be
familiar with more of the netCDF library.
In this we provide templates of common sequences of netCDF calls
needed for common uses. For clarity we present only the names of
routines; omit declarations and error checking; omit the type-specific
suffixes of routine names for variables and attributes; indent
statements that are typically invoked multiple times; and use ... to
represent arbitrary sequences of other statements. Full parameter lists
are described in laters.
1.1 Creating a NetCDF Dataset {#f77_Creating_a_NetCDF_Dataset}
-----------------------------
Here is a typical sequence of netCDF calls used to create a new netCDF
dataset:
NF_CREATE ! create netCDF dataset: enter define mode
...
NF_DEF_DIM ! define dimensions: from name and length
...
NF_DEF_VAR ! define variables: from name, type, dims
...
NF_PUT_ATT ! assign attribute values
...
NF_ENDDEF ! end definitions: leave define mode
...
NF_PUT_VAR ! provide values for variable
...
NF_CLOSE ! close: save new netCDF dataset
Only one call is needed to create a netCDF dataset, at which point you
will be in the first of two netCDF modes. When accessing an open netCDF
dataset, it is either in define mode or data mode. In define mode, you
can create dimensions, variables, and new attributes, but you cannot
read or write variable data. In data mode, you can access data and
change existing attributes, but you are not permitted to create new
dimensions, variables, or attributes.
One call to NF\_DEF\_DIM is needed for each dimension created.
Similarly, one call to NF\_DEF\_VAR is needed for each variable
creation, and one call to a member of the NF\_PUT\_ATT family is needed
for each attribute defined and assigned a value. To leave define mode
and enter data mode, call NF\_ENDDEF.
Once in data mode, you can add new data to variables, change old values,
and change values of existing attributes (so long as the attribute
changes do not require more storage space). Single values may be written
to a netCDF variable with one of the members of the NF\_PUT\_VAR1
family, depending on what type of data you have to write. All the values
of a variable may be written at once with one of the members of the
NF\_PUT\_VAR family. Arrays or array crosss of a variable may be
written using members of the NF\_PUT\_VARA family. Subsampled array
sections may be written using members of the NF\_PUT\_VARS family.
Mapped arrays may be written using members of the NF\_PUT\_VARM
family. (Subsampled and mapped access are general forms of data access
that are explained later.)
Finally, you should explicitly close all netCDF datasets that have been
opened for writing by calling NF\_CLOSE. By default, access to the file
system is buffered by the netCDF library. If a program terminates
abnormally with netCDF datasets open for writing, your most recent
modifications may be lost. This default buffering of data is disabled by
setting the NF\_SHARE flag when opening the dataset. But even if this
flag is set, changes to attribute values or changes made in define mode
are not written out until NF\_SYNC or NF\_CLOSE is called.
1.2 Reading a NetCDF Dataset with Known Names {#f77_Reading_a_NetCDF_Dataset_with_Known_Names}
---------------------------------------------
Here we consider the case where you know the names of not only the
netCDF datasets, but also the names of their dimensions, variables, and
attributes. (Otherwise you would have to do "inquire" calls.) The order
of typical C calls to read data from those variables in a netCDF dataset
is:
NF_OPEN ! open existing netCDF dataset
...
NF_INQ_DIMID ! get dimension IDs
...
NF_INQ_VARID ! get variable IDs
...
NF_GET_ATT ! get attribute values
...
NF_GET_VAR ! get values of variables
...
NF_CLOSE ! close netCDF dataset
First, a single call opens the netCDF dataset, given the dataset name,
and returns a netCDF ID that is used to refer to the open netCDF dataset
in allbsequent calls.
Next, a call to NF\_INQ\_DIMID for each dimension of interest gets the
dimension ID from the dimension name. Similarly, each required variable
ID is determined from its name by a call to NF\_INQ\_VARID.Once variable
IDs are known, variable attribute values can be retrieved using the
netCDF ID, the variable ID, and the desired attribute name as input to a
member of the NF\_GET\_ATT family (typically NF\_GET\_ATT\_TEXT or
NF\_GET\_ATT\_DOUBLE) for each desired attribute. Variable data values
can be directly accessed from the netCDF dataset with calls to members
of the NF\_GET\_VAR1 family for single values, the NF\_GET\_VAR family
for entire variables, or various other members of the NF\_GET\_VARA,
NF\_GET\_VARS, or NF\_GET\_VARM families for array,bsampled or mapped
access.
Finally, the netCDF dataset is closed with NF\_CLOSE. There is no need
to close a dataset open only for reading.
1.3 Reading a netCDF Dataset with Unknown Names {#f77_Reading_a_netCDF_Dataset_with_Unknown_Names}
-----------------------------------------------
It is possible to write programs (e.g., generic software) which doch
things as processing every variable, without needing to know in advance
the names of these variables. Similarly, the names of dimensions and
attributes may be unknown.
Names and other information about netCDF objects may be obtained from
netCDF datasets by calling inquire functions. These return information
about a whole netCDF dataset, a dimension, a variable, or an attribute.
The following template illustrates how they are used:
NF_OPEN ! open existing netCDF dataset
...
NF_INQ ! find out what is in it
...
NF_INQ_DIM ! get dimension names, lengths
...
NF_INQ_VAR ! get variable names, types, shapes
...
NF_INQ_ATTNAME ! get attribute names
...
NF_INQ_ATT ! get attribute values
...
NF_GET_ATT ! get attribute values
...
NF_GET_VAR ! get values of variables
...
NF_CLOSE ! close netCDF dataset
As in the previous example, a single call opens the existing netCDF
dataset, returning a netCDF ID. This netCDF ID is given to the NF\_INQ
routine, which returns the number of dimensions, the number of
variables, the number of global attributes, and the ID of the unlimited
dimension, if there is one.
All the inquire functions are inexpensive to use and require no I/O,
since the information they provide is stored in memory when a netCDF
dataset is first opened.
Dimension IDs use consecutive integers, beginning at 1. Also dimensions,
once created, cannot be deleted. Therefore, knowing the number of
dimension IDs in a netCDF dataset means knowing all the dimension IDs:
they are the integers 1, 2, 3, ... up to the number of dimensions. For
each dimension ID, a call to the inquire function NF\_INQ\_DIM returns
the dimension name and length.
Variable IDs are also assigned from consecutive integers 1, 2, 3, ... up
to the number of variables. These can be used in NF\_INQ\_VAR calls to
find out the names, types, shapes, and the number of attributes assigned
to each variable.
Once the number of attributes for a variable is known,ccessive calls
to NF\_INQ\_ATTNAME return the name for each attribute given the netCDF
ID, variable ID, and attribute number. Armed with the attribute name, a
call to NF\_INQ\_ATT returns its type and length. Given the type and
length, you can allocate enough space to hold the attribute values. Then
a call to a member of the NF\_GET\_ATT family returns the attribute
values.
Once the IDs and shapes of netCDF variables are known, data values can
be accessed by calling a member of the NF\_GET\_VAR1 family for single
values, or members of the NF\_GET\_VAR, NF\_GET\_VARA, NF\_GET\_VARS, or
NF\_GET\_VARM for various kinds of array access.
1.4 Adding New Dimensions, Variables, Attributes {#f77_Adding_New_Dimensions__Variables__Attributes}
------------------------------------------------
An existing netCDF dataset can be extensively altered. New dimensions,
variables, and attributes can be added or existing ones renamed, and
existing attributes can be deleted. Existing dimensions, variables, and
attributes can be renamed. The following code template lists a typical
sequence of calls to add new netCDF components to an existing dataset:
NF_OPEN ! open existing netCDF dataset
...
NF_REDEF ! put it into define mode
...
NF_DEF_DIM ! define additional dimensions (if any)
...
NF_DEF_VAR ! define additional variables (if any)
...
NF_PUT_ATT ! define other attributes (if any)
...
NF_ENDDEF ! check definitions, leave define mode
...
NF_PUT_VAR ! provide new variable values
...
NF_CLOSE ! close netCDF dataset
A netCDF dataset is first opened by the NF\_OPEN call. This call puts
the open dataset in data mode, which means existing data values can be
accessed and changed, existing attributes can be changed (so long as
they do not grow), but nothing can be added. To add new netCDF
dimensions, variables, or attributes you must enter define mode, by
calling NF\_REDEF.In define mode, call NF\_DEF\_DIM to define new
dimensions, NF\_DEF\_VAR to define new variables, and a member of the
NF\_PUT\_ATT family to assign new attributes to variables or enlarge old
attributes.
You can leave define mode and reenter data mode, checking all the new
definitions for consistency and committing the changes to disk, by
calling NF\_ENDDEF. If you do not wish to reenter data mode, just call
NF\_CLOSE, which will have the effect of first calling NF\_ENDDEF.
Until the NF\_ENDDEF call, you may back out of all the redefinitions
made in define mode and restore the previous state of the netCDF dataset
by calling NF\_ABORT. You may also use the NF\_ABORT call to restore the
netCDF dataset to a consistent state if the call to NF\_ENDDEF fails. If
you have called NF\_CLOSE from definition mode and the implied call to
NF\_ENDDEF fails, NF\_ABORT will automatically be called to close the
netCDF dataset and leave it in its previous consistent state (before you
entered define mode).
At most one process should have a netCDF dataset open for writing at one
time. The library is designed to provide limitedpport for multiple
concurrent readers with one writer, via disciplined use of the NF\_SYNC
function and the NF\_SHARE flag. If a writer makes changes in define
mode,ch as the addition of new variables, dimensions, or attributes,
some means external to the library is necessary to prevent readers from
making concurrent accesses and to inform readers to call NF\_SYNC before
the next access.
1.5 Error Handling {#f77_Error_Handling_1_5}
------------------
The netCDF library provides the facilities needed to handle errors in a
flexible way. Each netCDF function returns an integer status value. If
the returned status value indicates an error, you may handle it in any
way desired, from printing an associated error message and exiting to
ignoring the error indication and proceeding (not recommended!). For
simplicity, the examples in this guide check the error status and call a
separate function to handle any errors.
The NF\_STRERROR function is available to convert a returned integer
error status into an error message string.
Occasionally, low-level I/O errors may occur in a layer below the netCDF
library. For example, if a write operation causes you to exceed disk
quotas or to attempt to write to a device that is no longer available,
you may get an error from a layer below the netCDF library, but the
rlting write error will still be reflected in the returned status
value.
1.6 Compiling and Linking with the NetCDF Library {#f77_Compiling_and_Linking_with_the_NetCDF_Library}
-------------------------------------------------
Details of how to compile and link a program that uses the netCDF C or
FORTRAN interfaces differ, depending on the operating system, the
available compilers, and where the netCDF library and include files are
installed. Nevertheless, we provide here examples of how to compile and
link a program that uses the netCDF library on a Unix platform, so that
you can adjust these examples to fit your installation.
Every FORTRAN file that references netCDF functions or constants must
contain an appropriate INCLUDE statement before the first
reference:
INCLUDE 'netcdf.inc'
Unless the netcdf.inc file is installed in a standard directory where
the FORTRAN compiler always looks, you must use the -I option when
invoking the compiler, to specify a directory where netcdf.inc is
installed, for example:
f77 -c -I/usr/local/include myprogram.f
Unless the netCDF library is installed in a standard directory where the
linker always looks, you must use the -L and -l options to link an
object file that uses the netCDF library. Since version 4.1.3, the
netCDF Fortran library (named ‘libnetcdff’) is distinct from the netCDF
C library (named ‘libnetcdf’), but depends on it. If it is installed as
a shared library, you need only use ‘-lnetcdff’ to specify the Fortran
library for linking.
For example, if installed as a shared library, use something like:
f77 -o myprogram myprogram.o -L/usr/local/lib -lnetcdff
If installed as a static library, you will at least need to mention the
netCDF C library and perhaps other libraries,ch as hdf5 or curl,
depending on how the C library was built. For example:
f77 -o myprogram myprogram.o -L/usr/local/lib -lnetcdff -lnetcdf
Use of the nf-config utility program, installed as part of the
netcdf-fortran software, provides an easier way to compile and link,
without needing to know the details of where the library has been
installed, or whether it is installed as a shared or static library.
To see all the options for ‘nf-config’, invoke it with the ‘–help’
argument.
Here’s an example of how you could use ‘nf-config’ to compile and link a
Fortran program in one step:
f77 myprogram.f -o myprogram `nf-config --fflags --flibs`
If it is installed on your system, you could also use the ‘pkg-config’
utility to compile and link Fortran programs with the netCDF libraries.
This is especially useful in Makefiles, to ilate them from changes to
library versions and dependencies. Here is an example of how you could
compile and link a Fortran program with netCDF libraries using
pkg-config:
export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
f77 myprogram.f -o myprogram `pkg-config --cflags --libs netcdf-fortran`
where here ‘–cflags’ means compiler flags and ‘libs’ requests that the
approriate libraries be linked in.
2. Datasets {#f77_Datasets}
===========
2.1 Datasets Introduction {#f77_Datasets_Introduction}
-------------------------
This presents the interfaces of the netCDF functions that deal
with a netCDF dataset or the whole netCDF library.
A netCDF dataset that has not yet been opened can only be referred to by
its dataset name. Once a netCDF dataset is opened, it is referred to by
a netCDF ID, which is a small nonnegative integer returned when you
create or open the dataset. A netCDF ID is much like a file descriptor
in C or a logical unit number in FORTRAN. In any single program, the
netCDF IDs of distinct open netCDF datasets are distinct. A single
netCDF dataset may be opened multiple times and will then have multiple
distinct netCDF IDs; however at most one of the open instances of a
single netCDF dataset should permit writing. When an open netCDF dataset
is closed, the ID is no longer associated with a netCDF dataset.
Functions that deal with the netCDF library include:
- Get version of library.
- Get error message corresponding to a returned error code.
The operationspported on a netCDF dataset as a single object are:
- Create, given dataset name and whether to overwrite or not.
- Open for access, given dataset name and read or write intent.
- Put into define mode, to add dimensions, variables, or attributes.
- Take out of define mode, checking consistency of additions.
- Close, writing to disk if required.
- Inquire about the number of dimensions, number of variables, number
of global attributes, and ID of the unlimited dimension, if any.
- Synchronize to disk to makere it is current.
- Set and unset nofill mode for optimized sequential writes.
- After ammary of conventions used in describing the netCDF
interfaces, the rest of this presents a detailed description
of the interfaces for these operations.
2.2 NetCDF Library Interface Descriptions {#f77_NetCDF_Library_Interface_Descriptions}
-----------------------------------------
Each interface description for a particular netCDF function in this and
laters contains:
- a description of the purpose of the function;
- a FORTRAN function prototype that presents the type and order of the
formal parameters to the function;
- a description of each formal parameter in the C interface;
- a list of possible error conditions; and
- an example of a FORTRAN program fragment calling the netCDF function
(and perhaps other netCDF functions).
The examples follow a simple convention for error handling, always
checking the error status returned from each netCDF function call and
calling a handle\_error function in case an error was detected. For an
example ofch a function, see Section 5.2 "Get error message
corresponding to error status: nf\_strerror".
2.3 NF_STRERROR {#f77_NF_STRERROR}
----------------
The function NF\_STRERROR returns a static reference to an error message
string corresponding to an integer netCDF error status or to a system
error number, prmably returned by a previous call to some other
netCDF function. The list of netCDF error status codes is available in
the appropriate include file for each language binding.
### Usage
~~~
CHARACTER*80 FUNCTION NF_STRERROR(INTEGER NCERR)
~~~
`NCERR`
: An error status that might have been returned from a previous call
to some netCDF function.
### Errors
If you provide an invalid integer error status that does not correspond
to any netCDF error message or or to any system error message (as
understood by the system strerror function), NF\_STRERROR returns a
string indicating that there is noch error status.
### Example
Here is an example of a simple error handling function that uses
NF\_STRERROR to print the error message corresponding to the netCDF
error status returned from any netCDF function call and then exit:
~~~
INCLUDE 'netcdf.inc'
...
SUBROUTINE HANDLE_ERR(STATUS)
INTEGER STATUS
IF (STATUS .NE. NF_NOERR) THEN
PRINT *, NF_STRERROR(STATUS)
STOP 'Stopped'
ENDIF
END
~~~
2.4 Get netCDF library version: NF_INQ_LIBVERS {#f77_Get_netCDF_library_version_NF_INQ_LIBVERS}
------------------------------------------------
The function NF\_INQ\_LIBVERS returns a string identifying the version
of the netCDF library, and when it was built.
### Usage
~~~
CHARACTER*80 FUNCTION NF_INQ_LIBVERS()
~~~
### Errors
This function takes no arguments, and thus no errors are possible in its
invocation.
### Example
Here is an example using nf\_inq\_libvers to print the version of the
netCDF library with which the program is linked:
~~~
INCLUDE 'netcdf.inc'
...
PRINT *, NF_INQ_LIBVERS()
~~~
2.5 NF_CREATE {#f77_NF_CREATE}
--------------
This function creates a new netCDF dataset, returning a netCDF ID that
can sequently be used to refer to the netCDF dataset in other netCDF
function calls. The new netCDF dataset opened for write access and
placed in define mode, ready for you to add dimensions, variables, and
attributes.
A creation mode flag specifies whether to overwrite any existing dataset
with the same name and whether access to the dataset is shared.
### Usage
~~~
INTEGER FUNCTION NF_CREATE (CHARACTER*(*) PATH, INTEGER CMODE,
INTEGER ncid)
~~~
`PATH`: The file name of the new netCDF dataset.
`CMODE`: The creation mode flag. The following flags are available:
NF\_NOCLOBBER, NF\_SHARE, NF\_64BIT\_OFFSET, NF\_NETCDF4 and
NF\_CLASSIC\_MODEL. You can combine the affect of multiple flags in
a single argument by using the bitwise OR operator. For example, to
specify both NF\_NOCLOBBER and NF\_SHARE, you could provide the
argument OR(NF\_NOCLOBBER, NF\_SHARE).
A zero value (defined for convenience as NF_CLOBBER) specifies the
default behavior: overwrite any existing dataset with the same file
name and buffer and cache accesses for efficiency. The dataset will
be in netCDF classic format. See 'NetCDF Classic Format Limitations'
in The NetCDF Users Guide.
Setting NF\_NOCLOBBER means you do not want to clobber (overwrite)
an existing dataset; an error (NF_EEXIST) is returned if the
specified dataset already exists.
The NF\_SHARE flag is appropriate when one process may be writing
the dataset and one or more other processes reading the dataset
concurrently; it means that dataset accesses are not buffered and
caching is limited. Since the buffering scheme is optimized for
sequential access, programs that do not access data sequentially may
see some performance improvement by setting the NF\_SHARE flag. This
only applied to classic and 64-bit offset format files.
Setting NF\_64BIT\_OFFSET causes netCDF to create a 64-bit offset
format file, instead of a netCDF classic format file. The 64-bit
offset format imposes far fewer restrictions on very large (i.e.
over 2 GB) data files. See [(netcdf)Large File
Support](netcdf.html#Large-File-Support) ‘Large File
Support’ in The NetCDF Users Guide.
Setting NF\_NETCDF4 causes netCDF to create a netCDF-4/HDF5 format
file. Oring NF\_CLASSIC\_MODEL with NF\_NETCDF4 causes the netCDF
library to create a netCDF-4/HDF5 data file, with the netCDF classic
model enforced - none of the new features of the netCDF-4 data model
may be usedinch a file, for example groups and user-defined
types.
`ncid`
: Returned netCDF ID.
### Errors
NF\_CREATE returns the value NF\_NOERR if no errors occurred. Possible
causes of errors include:
- Passing a dataset name that includes a directory that does not
exist.
- Specifying a dataset name of a file that exists and also specifying
NF\_NOCLOBBER.
- Specifying a meaningless value for the creation mode.
- Attempting to create a netCDF dataset in a directory where you don’t
have permission to create files.
### Example
In this example we create a netCDF dataset named foo.nc; we want the
dataset to be created in the current directory only if a dataset with
that name does not already exist:
~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS
...
STATUS = NF_CREATE('foo.nc', NF_NOCLOBBER, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~
2.6 NF__CREATE {#f77_F__CREATE}
----------------
This function is a variant of NF\_CREATE, NF\_\_CREATE (note the double
underscore) allows users to specify two tuning parameters for the file
that it is creating. These tuning parameters are not written to the data
file, they are only used for so long as the file remains open after an
NF\_\_CREATE.
This function creates a new netCDF dataset, returning a netCDF ID that
canbsequently be used to refer to the netCDF dataset in other netCDF
function calls. The new netCDF dataset opened for write access and
placed in define mode, ready for you to add dimensions, variables, and
attributes.
A creation mode flag specifies whether to overwrite any existing dataset
with the same name and whether access to the dataset is shared.
### Usage
~~~
INTEGER FUNCTION NF__CREATE (CHARACTER*(*) PATH, INTEGER CMODE, INTEGER INITIALSZ,
INTEGER BUFRSIZEHINT, INTEGER ncid)
~~~
`PATH`
: The file name of the new netCDF dataset.
`CMODE`
: The creation mode flag. The following flags are available:
NF\_NOCLOBBER, NF\_SHARE, NF\_64BIT\_OFFSET, NF\_NETCDF4, and
NF\_CLASSIC\_MODEL.
Setting NF\_NOCLOBBER means you do not want to clobber (overwrite)
an existing dataset; an error (NF\_EEXIST) is returned if the
specified dataset already exists.
The NF\_SHARE flag is appropriate when one process may be writing
the dataset and one or more other processes reading the dataset
concurrently; it means that dataset accesses are not buffered and
caching is limited. Since the buffering scheme is optimized for
sequential access, programs that do not access data sequentially may
see some performance improvement by setting the NF\_SHARE flag. This
flag has no effect with netCDF-4/HDF5 files.
Setting NF\_64BIT\_OFFSET causes netCDF to create a 64-bit offset
format file, instead of a netCDF classic format file. The 64-bit
offset format imposes far fewer restrictions on very large (i.e.
over 2 GB) data files. See [(netcdf)Large File
Support](netcdf.html#Large-File-Support) ‘Large File
Support’ in The NetCDF Users Guide.
Setting NF\_CLASSIC\_MODEL causes netCDF to enforce the classic data
model in this file. (This only has effect for netCDF-4/HDF5 files,
as classic and 64-bit offset files always use the classic model.)
When used with NF\_NETCDF4, this flag eres that the rlting
netCDF-4/HDF5 file may never contain any new constructs from the
enhanced data model. That is, it cannot contain groups, user defined
types, multiple unlimited dimensions, or new atomic types. The
advantage of this restriction is thatch files are guarenteed to
work with existing netCDF software.
A zero value (defined for convenience as NF\_CLOBBER) specifies the
default behavior: overwrite any existing dataset with the same file
name and buffer and cache accesses for efficiency. The dataset will
be in netCDF classic format. See [(netcdf)NetCDF Classic Format
Limitations](netcdf.html#NetCDF-Classic-Format-Limitations)
‘NetCDF Classic Format Limitations’ in The NetCDF Users Guide.
`INITIALSZ`
: This parameter sets the initial size of the file at creation time.
`BUFRSIZEHINT`
: The argument referenced by BUFRSIZEHINT controls a space ves time
tradeoff, memory allocated in the netcdf library ves number of
system calls.
Because of internal requirements, the value may not be set to
exactly the value requested. The actual value chosen is returned by
reference.
Using the value NF\_SIZEHINT\_DEFAULT causes the library to choose a
default. How the system chooses the default depends on the system.
On many systems, the "preferred I/O block size" is available from
the stat() system call, struct stat member st\_blksize. If this is
available it is used. Lacking that, twice the system pagesize is
used.
Lacking a call to discover the system pagesize, we just set default
bufrsize to 8192.
The BUFRSIZE is a property of a given open netcdf descriptor ncid,
it is not a persistent property of the netcdf dataset.
`ncid`
: Returned netCDF ID.
### Errors
NF\_\_CREATE returns the value NF\_NOERR if no errors occurred. Possible
causes of errors include:
- Passing a dataset name that includes a directory that does not
exist.
- Specifying a dataset name of a file that exists and also specifying
NF\_NOCLOBBER.
- Specifying a meaningless value for the creation mode.
- Attempting to create a netCDF dataset in a directory where you don’t
have permission to create files.
### Example
In this example we create a netCDF dataset named foo.nc; we want the
dataset to be created in the current directory only if a dataset with
that name does not already exist:
~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS, INITIALSZ, BUFRSIZEHINT
...
INITIALSZ = 2048
BUFRSIZEHINT = 1024
STATUS = NF__CREATE('foo.nc', NF_NOCLOBBER, INITIALSZ, BUFRSIZEHINT, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~
2.7 NF_CREATE_PAR {#f77_NF_CREATE_PAR}
-------------------
This function is a variant of nf\_create, nf\_create\_par allows users
to open a file on a MPI/IO or MPI/Posix parallel file system.
The parallel parameters are not written to the data file, they are only
used for so long as the file remains open after an nf\_create\_par.
This function is only available if the netCDF library was built with
parallel I/O.
This function creates a new netCDF dataset, returning a netCDF ID that
canbsequently be used to refer to the netCDF dataset in other netCDF
function calls. The new netCDF dataset opened for write access and
placed in define mode, ready for you to add dimensions, variables, and
attributes.
When a netCDF-4 file is created for parallel access, independent
operations are the default. To use collective access on a variable, See
section [Change between Collective and Independent Parallel Access:
NF\_VAR\_PAR\_ACCESS](#NF_005fVAR_005fPAR_005fACCESS).
### Usage
~~~
INTEGER FUNCTION NF_CREATE_PAR(CHARACTER*(*) PATH, INTEGER CMODE,
INTEGER MPI_COMM, INTEGER MPI_INFO,
INTEGER ncid)
~~~
`PATH`
: The file name of the new netCDF dataset.
`CMODE`
: The creation mode flag. The following flags are available:
NF\_NOCLOBBER, NF\_NETCDF4 and NF\_CLASSIC\_MODEL. You can combine
the affect of multiple flags in a single argument by using the
bitwise OR operator. For example, to specify both NF\_NOCLOBBER and
NF\_NETCDF4, you could provide the argument OR(NF\_NOCLOBBER,
NF\_NETCDF4).
Setting NF\_NETCDF4 causes netCDF to create a netCDF-4/HDF5 format
file. Oring NF\_CLASSIC\_MODEL with NF\_NETCDF4 causes the netCDF
library to create a netCDF-4/HDF5 data file, with the netCDF classic
model enforced - none of the new features of the netCDF-4 data model
may be usedinch a file, for example groups and user-defined
types.
Only netCDF-4/HDF5 files may be used with parallel I/O.
`MPI_COMM`
: The MPI communicator.
`MPI_INFO`
: The MPI info.
`ncid`
: Returned netCDF ID.
### Errors
NF\_CREATE returns the value NF\_NOERR if no errors occurred. Possible
causes of errors include:
- Passing a dataset name that includes a directory that does not
exist.
- Specifying a dataset name of a file that exists and also specifying
NF\_NOCLOBBER.
- Specifying a meaningless value for the creation mode.
- Attempting to create a netCDF dataset in a directory where you don’t
have permission to create files.
### Example
This example is from test program nf\_test/ftst\_parallel.F.
~~~
! Create the netCDF file.
mode_flag = IOR(nf_netcdf4, nf_classic_model)
retval = nf_create_par(FILE_NAME, mode_flag, MPI_COMM_WORLD,
$ MPI_INFO_NULL, ncid)
if (retval .ne. nf_noerr) stop 2
~~~
2.8 NF_OPEN {#f77_NF_OPEN_}
------------
The function NF\_OPEN opens an existing netCDF dataset for access.
### Usage
~~~
INTEGER FUNCTION NF_OPEN(CHARACTER*(*) PATH, INTEGER OMODE, INTEGER ncid)
~~~
`PATH`
: File name for netCDF dataset to be opened. This may be an OPeNDAP
URL if DAPpport is enabled.
`OMODE`
: A zero value (or NF\_NOWRITE) specifies: open the dataset with
read-only access, buffering and caching accesses for efficiency.
Otherwise, the creation mode is NF\_WRITE, NF\_SHARE, or
OR(NF\_WRITE, NF\_SHARE). Setting the NF\_WRITE flag opens the
dataset with read-write access. ("Writing" means any kind of change
to the dataset, including appending or changing data, adding or
renaming dimensions, variables, and attributes, or deleting
attributes.) The NF\_SHARE flag is appropriate when one process may
be writing the dataset and one or more other processes reading the
dataset concurrently; it means that dataset accesses are not
buffered and caching is limited. Since the buffering scheme is
optimized for sequential access, programs that do not access data
sequentially may see some performance improvement by setting the
NF\_SHARE flag.
`ncid`
: Returned netCDF ID.
### Errors
NF\_OPEN returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- The specified netCDF dataset does not exist.
- A meaningless mode was specified.
### Example
Here is an example using NF\_OPEN to open an existing netCDF dataset
named foo.nc for read-only, non-shared access:
~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS
...
STATUS = NF_OPEN('foo.nc', 0, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~
2.9 NF__OPEN {#NF__OPEN_}
--------------
The function NF\_OPEN opens an existing netCDF dataset for access, with
a performance tuning parameter.
### Usage
~~~
INTEGER FUNCTION NF_OPEN(CHARACTER*(*) PATH, INTEGER OMODE, INTEGER
BUFRSIZEHINT, INTEGER ncid)
~~~
`PATH`
: File name for netCDF dataset to be opened.
`OMODE`
: A zero value (or NF\_NOWRITE) specifies: open the dataset with
read-only access, buffering and caching accesses for efficiency
Otherwise, the creation mode is NF\_WRITE, NF\_SHARE, or
OR(NF\_WRITE,NF\_SHARE). Setting the NF\_WRITE flag opens the
dataset with read-write access. ("Writing" means any kind of change
to the dataset, including appending or changing data, adding or
renaming dimensions, variables, and attributes, or deleting
attributes.) The NF\_SHARE flag is appropriate when one process may
be writing the dataset and one or more other processes reading the
dataset concurrently; it means that dataset accesses are not
buffered and caching is limited. Since the buffering scheme is
optimized for sequential access, programs that do not access data
sequentially may see some performance improvement by setting the
NF\_SHARE flag.
`BUFRSIZEHINT`
: This argument controls a space ves time tradeoff, memory
allocated in the netcdf library ves number of system calls.
Because of internal requirements, the value may not be set to
exactly the value requested. The actual value chosen is returned by
reference.
Using the value NF\_SIZEHINT\_DEFAULT causes the library to choose a
default. How the system chooses the default depends on the system.
On many systems, the "preferred I/O block size" is available from
the stat() system call, struct stat member st\_blksize. If this is
available it is used. Lacking that, twice the system pagesize is
used.
Lacking a call to discover the system pagesize, we just set default
bufrsize to 8192.
The bufrsize is a property of a given open netcdf descriptor ncid,
it is not a persistent property of the netcdf dataset.
`ncid`
: Returned netCDF ID.
### Errors
NF\_\_OPEN returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- The specified netCDF dataset does not exist.
- A meaningless mode was specified.
### Example
Here is an example using NF\_\_OPEN to open an existing netCDF dataset
named foo.nc for read-only, non-shared access:
~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS, BUFRSIZEHINT
...
BUFRSIZEHINT = 1024
STATUS = NF_OPEN('foo.nc', 0, BUFRSIZEHINT, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~
2.10 NF_OPEN_PAR {#f77_NF_OPEN_PAR}
------------------
This function opens a netCDF-4 dataset for parallel access.
This function is only available if the netCDF library was built with a
HDF5 library for which –enable-parallel was used, and which was linked
(like HDF5) to MPI libraries.
This opens the file using either MPI-IO or MPI-POSIX. The file must be a
netCDF-4 file. (That is, it must have been created using NF\_NETCDF4 in
the creation mode).
This function is only available if netCDF-4 was build with a version of
the HDF5 library which was built with –enable-parallel.
Before either HDF5 or netCDF-4 can be installed withpport for
parallel programming, and MPI layer must also be installed on the
machine, and ally a parallel file system.
NetCDF-4 exposes the parallel access functionality of HDF5. For more
information about what is required to install and use the parallel
access functions, see the HDF5 web site.
When a netCDF-4 file is opened for parallel access, collective
operations are the default. To use independent access on a variable, See
section [Change between Collective and Independent Parallel Access:
NF\_VAR\_PAR\_ACCESS](#NF_005fVAR_005fPAR_005fACCESS).
Usage
-----
~~~
INTEGER FUNCTION NF_OPEN_PAR(CHARACTER*(*) PATH, INTEGER OMODE,
INTEGER MPI_COMM, INTEGER MPI_INFO,
INTEGER ncid)
~~~
`PATH`
: File name for netCDF dataset to be opened.
`OMODE`
: A zero value (or NF\_NOWRITE) specifies: open the dataset with
read-only access.
Otherwise, the mode may be NF\_WRITE. Setting the NF\_WRITE flag
opens the dataset with read-write access. ("Writing" means any kind
of change to the dataset, including appending or changing data,
adding or renaming dimensions, variables, and attributes, or
deleting attributes.)
Setting NF\_NETCDF4 is not necessary (or allowed). The file type is
detected automatically.
`MPI_COMM`
: The MPI communicator.
`MPI_INFO`
: The MPI info.
`ncid`
: Returned netCDF ID.
Errors
------
NF\_OPEN returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- The specified netCDF dataset does not exist.
- A meaningless mode was specified.
- Not a netCDF-4 file.
Example
-------
This example is from the test program nf\_test/ftst\_parallel.F.
~~~~
! Reopen the file.
retval = nf_open_par(FILE_NAME, nf_nowrite, MPI_COMM_WORLD,
$ MPI_INFO_NULL, ncid)
if (retval .ne. nf_noerr) stop 2
~~~~
2.11 NF_REDEF {#f77_NF-REDEF}
--------------
The function NF\_REDEF puts an open netCDF dataset into define mode, so
dimensions, variables, and attributes can be added or renamed and
attributes can be deleted.
Usage
-----
INTEGER FUNCTION NF_REDEF(INTEGER NCID)
`NCID`
: netCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
Errors
------
NF\_REDEF returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- The specified netCDF dataset is already in define mode.
- The specified netCDF dataset was opened for read-only.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_REDEF to open an existing netCDF dataset
named foo.nc and put it into define mode:
~~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID) ! open dataset
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_REDEF(NCID) ! put in define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~~
2.12 NF_ENDDEF {#f77_NF-ENDDEF}
---------------
The function NF\_ENDDEF takes an open netCDF dataset out of define mode.
The changes made to the netCDF dataset while it was in define mode are
checked and committed to disk if no problems occurred. Non-record
variables may be initialized to a "fill value" as well (see
[NF\_SET\_FILL](#NF_005fSET_005fFILL)). The netCDF dataset is then
placed in data mode, so variable data can be read or written.
This call may involve copying data under some circumstances. See
[(netcdf)File Structure and
Performance](netcdf.html#File-Structure-and-Performance) ‘File
Structure and Performance’ in NetCDF Users’ Guide.
Usage
-----
INTEGER FUNCTION NF_ENDDEF(INTEGER NCID)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
Errors
------
NF\_ENDDEF returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- The specified netCDF dataset is not in define mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
The size of one or more variables exceed the size constraints for
whichever variant of the file format is in use). See [(netcdf)Large
File Support](netcdf.html#Large-File-Support) ‘Large File
Support’ in The NetCDF Users Guide.
Example
-------
Here is an example using NF\_ENDDEF to finish the definitions of a new
netCDF dataset named foo.nc and put it into data mode:
~~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS
...
STATUS = NF_CREATE('foo.nc', NF_NOCLOBBER, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
... ! create dimensions, variables, attributes
STATUS = NF_ENDDEF(NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~~
2.13 NF__ENDDEF {#f77_NF__ENDDEF}
-----------------
The function NF\_\_ENDDEF takes an open netCDF dataset out of define
mode. The changes made to the netCDF dataset while it was in define mode
are checked and committed to disk if no problems occurred. Non-record
variables may be initialized to a "fill value" as well (see
[NF\_SET\_FILL](#NF_005fSET_005fFILL)). The netCDF dataset is then
placed in data mode, so variable data can be read or written.
This call may involve copying data under some circumstances. See
[(netcdf)File Structure and
Performance](netcdf.html#File-Structure-and-Performance) ‘File
Structure and Performance’ in NetCDF Users’ Guide.
This function ames specific characteristics of the netcdf version 1
and version 2 file formats. Users should use nf\_enddef in most
circumstances. Although this function will be available in future netCDF
implementations, it may not continue to have any effect on performance.
The current netcdf file format has threes, the "header",
the data for fixed size variables, and the data for
variables which have an unlimited dimension (record variables).
The header begins at the beginning of the file. The index (offset) of
the beginning of the other twos is contained in the header.
Typically, there is no space between thes. This causes copying
overhead to accrue if one wishes to change the size of thes, as
may happen when changing names of things, text attribute values, adding
attributes or adding variables. Also, for buffered i/o, there may be
advantages to alignings in certain ways.
The minfree parameters allow one to control costs of future calls to
nf\_redef, nf\_enddef by requesting that minfree bytes be available at
the end of the.
The align parameters allow one to set the alignment of the beginning of
the correspondings. The beginning of the is rounded up
to an index which is a multiple of the align parameter. The flag value
ALIGN\_CHUNK tells the library to use the bufrsize (see above) as the
align parameter.
The file format requires mod 4 alignment, so the align parameters are
silently rounded up to multiples of 4. The al call,
nf_enddef(ncid);
is equivalent to
nf_enddef(ncid, 0, 4, 0, 4);
The file format does not contain a "record size" value, this is
calculated from the sizes of the record variables. This unfortunate fact
prevents us from providing minfree and alignment control of the
"records" in a netcdf file. If you add a variable which has an unlimited
dimension, the third will always be copied with the new variable
added.
Usage
-----
INTEGER FUNCTION NF_ENDDEF(INTEGER NCID, INTEGER H_MINFREE, INTEGER V_ALIGN,
INTEGER V_MINFREE, INTEGER R_ALIGN)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`H_MINFREE`
: Sets the pad at the end of the "header".
`V_ALIGN`
: Controls the alignment of the beginning of the data for
fixed size variables.
`V_MINFREE`
: Sets the pad at the end of the data for fixed size
variables.
`R_ALIGN`
: Controls the alignment of the beginning of the data for
variables which have an unlimited dimension (record variables).
Errors
------
NF\_\_ENDDEF returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The specified netCDF dataset is not in define mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
- The size of one or more variables exceed the size constraints for
whichever variant of the file format is in use). See [(netcdf)Large
File Support](netcdf.html#Large-File-Support) ‘Large File
Support’ in The NetCDF Users Guide.
Example
-------
Here is an example using NF\_\_ENDDEF to finish the definitions of a new
netCDF dataset named foo.nc and put it into data mode:
~~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS, H_MINFREE, V_ALIGN, V_MINFREE, R_ALIGN
...
STATUS = NF_CREATE('foo.nc', NF_NOCLOBBER, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
... ! create dimensions, variables, attributes
H_MINFREE = 512
V_ALIGN = 512
V_MINFREE = 512
R_ALIGN = 512
STATUS = NF_ENDDEF(NCID, H_MINFREE, V_ALIGN, V_MINFREE, R_ALIGN)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~~
2.14 NF_CLOSE {#f77_NF-CLOSE}
--------------
The function NF\_CLOSE closes an open netCDF dataset. If the dataset is
in define mode, NF\_ENDDEF will be called before closing. (In this case,
if NF\_ENDDEF returns an error, NF\_ABORT will automatically be called
to restore the dataset to the consistent state before define mode was
last entered.) After an open netCDF dataset is closed, its netCDF ID may
be reassigned to the next netCDF dataset that is opened or created.
Usage
-----
INTEGER FUNCTION NF_CLOSE(INTEGER NCID)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
Errors
------
NF\_CLOSE returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- Define mode was entered and the automatic call made to NF\_ENDDEF
failed.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_CLOSE to finish the definitions of a new
netCDF dataset named foo.nc and release its netCDF ID:
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS
...
STATUS = NF_CREATE('foo.nc', NF_NOCLOBBER, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
... ! create dimensions, variables, attributes
STATUS = NF_CLOSE(NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
2.15 NF_INQ Family {#f77_NF-INQ-Family}
-------------------
Members of the NF\_INQ family of functions return information about an
open netCDF dataset, given its netCDF ID. Dataset inquire functions may
be called from either define mode or data mode. The first function,
NF\_INQ, returns values for the number of dimensions, the number of
variables, the number of global attributes, and the dimension ID of the
dimension defined with unlimited length, if any. The other functions in
the family each return just one of these items of information.
For FORTRAN, these functions include NF\_INQ, NF\_INQ\_NDIMS,
NF\_INQ\_NVARS, NF\_INQ\_NATTS, and NF\_INQ\_UNLIMDIM. An additional
function, NF\_INQ\_FORMAT, returns the (rarely needed) format version.
No I/O is performed when these functions are called, since the required
information is available in memory for each open netCDF dataset.
Usage
-----
INTEGER FUNCTION NF_INQ (INTEGER NCID, INTEGER ndims,
INTEGER nvars,INTEGER ngatts,
INTEGER unlimdimid)
INTEGER FUNCTION NF_INQ_NDIMS (INTEGER NCID, INTEGER ndims)
INTEGER FUNCTION NF_INQ_NVARS (INTEGER NCID, INTEGER nvars)
INTEGER FUNCTION NF_INQ_NATTS (INTEGER NCID, INTEGER ngatts)
INTEGER FUNCTION NF_INQ_UNLIMDIM (INTEGER NCID, INTEGER unlimdimid)
INTEGER FUNCTION NF_INQ_FORMAT (INTEGER NCID, INTEGER format)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`ndims`
: Returned number of dimensions defined for this netCDF dataset.
`nvars`
: Returned number of variables defined for this netCDF dataset.
`ngatts`
: Returned number of global attributes defined for this netCDF
dataset.
`unlimdimid`
: Returned ID of the unlimited dimension, if there is one for this
netCDF dataset. If no unlimited length dimension has been defined,
-1 is returned.
`format`
: Returned format version, one of NF\_FORMAT\_CLASSIC,
NF\_FORMAT\_64BIT, NF\_FORMAT\_NETCDF4,
NF\_FORMAT\_NETCDF4\_CLASSIC.
Errors
------
All members of the NF\_INQ family return the value NF\_NOERR if no
errors occurred. Otherwise, the returned status indicates an error.
Possible causes of errors include:
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_INQ to find out about a netCDF dataset
named foo.nc:
~~~~
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, NDIMS, NVARS, NGATTS, UNLIMDIMID
...
STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ(NCID, NDIMS, NVARS, NGATTS, UNLIMDIMID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
~~~~
2.16 NF_SYNC {#f77_NF-SYNC}
-------------
The function NF\_SYNC offers a way to synchronize the disk copy of a
netCDF dataset with in-memory buffers. There are two reasons you might
want to synchronize after writes:
- To minimize data loss in case of abnormal termination, or
- To make data available to other processes for reading immediately
after it is written. But note that a process that already had the
dataset open for reading would not see the number of records
increase when the writing process calls NF\_SYNC; to accomplish
this, the reading process must call NF\_SYNC.
This function is backward-compatible with previous versions of the
netCDF library. The intent was to allow sharing of a netCDF dataset
among multiple readers and one writer, by having the writer call
NF\_SYNC after writing and the readers call NF\_SYNC before each read.
For a writer, this flushes buffers to disk. For a reader, it makesre
that the next read will be from disk rather than from previously cached
buffers, so that the reader will see changes made by the writing process
(e.g., the number of records written) without having to close and reopen
the dataset. If you are only accessing a small amount of data, it can be
expensive in computer resources to always synchronize to disk after
every write, since you are giving up the benefits of buffering.
An easier way to accomplish sharing (and what is now recommended) is to
have the writer and readers open the dataset with the NF\_SHARE flag,
and then it will not be necessary to call NF\_SYNC at all. However, the
NF\_SYNC function still provides finer granularity than the NF\_SHARE
flag, if only a few netCDF accesses need to be synchronized among
processes.
It is important to note that changes to the ancillary data,ch as
attribute values, are not propagated automatically by use of the
NF\_SHARE flag. Use of the NF\_SYNC function is still required for this
purpose.
Sharing datasets when the writer enters define mode to change the data
schema requires extra care. In previous releases, after the writer left
define mode, the readers were left looking at an old copy of the
dataset, since the changes were made to a new copy. The only way readers
could see the changes was by closing and reopening the dataset. Now the
changes are made in place, but readers have no knowledge that their
internal tables are now inconsistent with the new dataset schema. If
netCDF datasets are shared across redefinition, some mechanism external
to the netCDF library must be provided that prevents access by readers
during redefinition and causes the readers to call NF\_SYNC before any
subsequent access.
When calling NF\_SYNC, the netCDF dataset must be in data mode. A netCDF
dataset in define mode is synchronized to disk only when NF\_ENDDEF is
called. A process that is reading a netCDF dataset that another process
is writing may call NF\_SYNC to get updated with the changes made to the
data by the writing process (e.g., the number of records written),
without having to close and reopen the dataset.
Data is automatically synchronized to disk when a netCDF dataset is
closed, or whenever you leave define mode.
Usage
-----
INTEGER FUNCTION NF_SYNC(INTEGER NCID)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
Errors
------
NF\_SYNC returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- The netCDF dataset is in define mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_SYNC to synchronize the disk writes of a
netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! write data or change attributes
...
STATUS = NF_SYNC(NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
2.17 NF_ABORT {#f77_NF-ABORT}
--------------
You no longer need to call this function, since it is called
automatically by NF\_CLOSE in case the dataset is in define mode and
something goes wrong with committing the changes. The function NF\_ABORT
just closes the netCDF dataset, if not in define mode. If the dataset is
being created and is still in define mode, the dataset is deleted. If
define mode was entered by a call to NF\_REDEF, the netCDF dataset is
restored to its state before definition mode was entered and the dataset
is closed.
Usage
-----
INTEGER FUNCTION NF_ABORT(INTEGER NCID)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
Errors
------
NF\_ABORT returns the value NF\_NOERR if no errors occurred. Otherwise,
the returned status indicates an error. Possible causes of errors
include:
- When called from define mode while creating a netCDF dataset,
deletion of the dataset failed.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_ABORT to back out of redefinitions of a
dataset named foo.nc:
~~~~
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, LATID
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_REDEF(NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_DEF_DIM(NCID, 'LAT', 18, LATID)
IF (STATUS .NE. NF_NOERR) THEN ! dimension definition failed
CALL HANDLE_ERR(STATUS)
STATUS = NF_ABORT(NCID) ! abort redefinitions
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
ENDIF
...
~~~~
2.18 NF_SET_FILL {#f77_NF-SET-FILL}
------------------
This function is intended for advanced usage, to optimize writes under
some circumstances described below. The function NF\_SET\_FILL sets the
fill mode for a netCDF dataset open for writing and returns the current
fill mode in a return parameter. The fill mode can be specified as
either NF\_FILL or NF\_NOFILL. The default behavior corresponding to
NF\_FILL is that data is pre-filled with fill values, that is fill
values are written when you create non-record variables or when you
write a value beyond data that has not yet been written. This makes it
possible to detect attempts to read data before it was written. See
section [Fill Values](#Fill-Values), for more information on the use of
fill values. See [(netcdf)Attribute
Conventions](netcdf.html#Attribute-Conventions) ‘Attribute
Conventions’ in The NetCDF Users Guide, for information about how to
define your own fill values.
The behavior corresponding to NF\_NOFILL overrides the default behavior
of prefilling data with fill values. This can be used to enhance
performance, because it avoids the duplicate writes that occur when the
netCDF library writes fill values that are later overwritten with data.
A value indicating which mode the netCDF dataset was already in is
returned. You can use this value to temporarily change the fill mode of
an open netCDF dataset and then restore it to the previous mode.
After you turn on NF\_NOFILL mode for an open netCDF dataset, you must
be certain to write valid data in all the positions that will later be
read. Note that nofill mode is only a transient property of a netCDF
dataset open for writing: if you close and reopen the dataset, it will
revert to the default behavior. You can also revert to the default
behavior by calling NF\_SET\_FILL again to explicitly set the fill mode
to NF\_FILL.
There are three situations where it is advantageous to set nofill mode:
1. Creating and initializing a netCDF dataset. In this case, you should
set nofill mode before calling NF\_ENDDEF and then write completely
all non-record variables and the initial records of all the record
variables you want to initialize.
2. Extending an existing record-oriented netCDF dataset. Set nofill
mode after opening the dataset for writing, then append the
additional records to the dataset completely, leaving no intervening
unwritten records.
3. Adding new variables that you are going to initialize to an existing
netCDF dataset. Set nofill mode before calling NF\_ENDDEF then write
all the new variables completely.
If the netCDF dataset has an unlimited dimension and the last record was
written while in nofill mode, then the dataset may be shorter than if
nofill mode was not set, but this will be completely transparent if you
access the data only through the netCDF interfaces.
The use of this feature may not be available (or even needed) in future
releases. Programmers are cautioned against heavy reliance upon this
feature.
Usage
-----
INTEGER FUNCTION NF_SET_FILL(INTEGER NCID, INTEGER FILLMODE,
INTEGER old_mode)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`FILLMODE`
: Desired fill mode for the dataset, either NF\_NOFILL or NF\_FILL.
`old_mode`
: Returned current fill mode of the dataset before this call, either
NF\_NOFILL or NF\_FILL.
Errors
------
NF\_SET\_FILL returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The specified netCDF ID does not refer to an open netCDF dataset.
- The specified netCDF ID refers to a dataset open for read-only
access.
- The fill mode argument is neither NF\_NOFILL nor NF\_FILL..
Example
-------
Here is an example using NF\_SET\_FILL to set nofill mode forbsequent
writes of a netCDF dataset named foo.nc:
~~~~
INCLUDE 'netcdf.inc'
...
INTEGER NCID, STATUS, OMODE
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! write data with default prefilling behavior
...
STATUS = NF_SET_FILL(NCID, NF_NOFILL, OMODE)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! write data with no prefilling
...
~~~~
2.19 NF_SET_DEFAULT_FORMAT {#f77_NF-SET-DEFAULT-FORMAT}
-----------------------------
This function is intended for advanced users.
In version 3.6, netCDF introduced a new data format, the first change in
the underlying binary data format since the netCDF interface was
released. The new format, 64-bit offset format, was introduced to
greatly relax the limitations on creating very large files.
In version 4.0, another new binary format was introduced: netCDF-4/HDF5.
Users are warned that creating files in the 64-bit offset format makes
them unreadable by the netCDF library prior to version 3.6.0, and
creating files in netcdf-4/HDF5 format makes them unreadable by the
netCDF library prior to version 4.0. For reasons of compatibility, users
should continue to create files in netCDF classic format.
Users who do want to use 64-bit offset or netCDF-4/HDF5 format files can
create them directory from NF\_CREATE, using the proper cmode flag. (see
section [NF\_CREATE](#NF_005fCREATE)).
The function NF\_SET\_DEFAULT\_FORMAT allows the user to change the
format of the netCDF file to be created by future calls to NF\_CREATE
without changing the cmode flag.
This allows the user to convert a program to use the new formats without
changing all calls the NF\_CREATE.
Once the default format is set, all future created files will be in the
desired format.
Constants are provided in the netcdf.inc file to be used with this
function: nf\_format\_classic, nf\_format\_64bit, nf\_format\_netcdf4
and nf\_format\_netcdf4\_classic.
Usage
-----
INTEGER FUNCTION NF_SET_DEFAULT_FORMAT(INTEGER FORMAT, INTEGER OLD_FORMT)
`FORMAT`
: Either nf\_format\_classic, nf\_format\_64bit, nf\_format\_netcdf4
or nf\_format\_netcdf4\_classic.
`OLD_FORMAT`
: The default format at the time the function is called is returned
here.
Errors
------
The following error codes may be returned by this function:
- An NF\_EINVAL error is returned if an invalid default format is
specified.
Example
-------
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, OLD_FORMAT
...
STATUS = NF_SET_DEFAULT_FORMAT(nf_format_64bit, OLD_FORMAT)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
2.20 Set HDF5 Chunk Cache for Future File Opens/Creates: NF_SET_CHUNK_CACHE {#f77_Set-HDF5-Chunk}
------------------------------------------------------------------------------
This function changes the chunk cache settings in the HDF5 library. The
settings apply forbsequent file opens/creates. This function does not
change the chunk cache settings of already open files.
This affects the per-file chunk cache which the HDF5 layer maintains.
The chunk cache size can be tuned for better performance.
For more information, see the documentation for the H5Pset\_cache()
function in the HDF5 library at the HDF5 website:
[http://hdfgroup.org/HDF5/](http://hdfgroup.org/HDF5/).
Usage
-----
INTEGER NF_SET_CHUNK_CACHE(INTEGER SIZE, INTEGER NELEMS, INTEGER PREEMPTION);
`SIZE`
: The total size of the raw data chunk cache in MegaBytes.
`NELEMS`
: The number slots in the per-variable chunk cache (should be a prime
number larger than the number of chunks in the cache).
`PREEMPTION`
: The preemtion value must be between 0 and 100 inclusive and
indicates how much chunks that have been fully read are favored for
preemption. A value of zero means fully read chunks are treated no
differently than other chunks (the preemption is strictly LRU) while
a value of 100 means fully read chunks are always preempted before
other chunks.
Return Codes
------------
`NF_NOERR`
: No error.
`NF_EINVAL`
: Parameters size and nelems must be non-zero positive integers, and
preemption must be between zero and 100 (inclusive). An NF\_EINVAL
will be returned otherwise.
2.21 Get the HDF5 Chunk Cache Settings for Future File Opens/Creates: NF_GET_CHUNK_CACHE {#f77_NF-GET-CHUNK-CACHE}
-------------------------------------------------------------------------------------------
This function gets the chunk cache settings for the HDF5 library. The
settings apply forbsequent file opens/creates.
This affects the per-file chunk cache which the HDF5 layer maintains.
The chunk cache size can be tuned for better performance.
For more information, see the documentation for the H5Pget\_cache()
function in the HDF5 library at the HDF5 website:
[http://hdfgroup.org/HDF5/](http://hdfgroup.org/HDF5/).
Usage
-----
INTEGER NC_GET_CHUNK_CACHE(INTEGER SIZE, INTEGER NELEMS, INTEGER PREEMPTION);
`SIZE`
: The total size of the raw data chunk cache will be put here.
`NELEMS`
: The number of chunk slots in the raw data chunk cache hash table
will be put here.
`PREEMPTION`
: The preemption will be put here. The preemtion value is between 0
and 100 inclusive and indicates how much chunks that have been fully
read are favored for preemption. A value of zero means fully read
chunks are treated no differently than other chunks (the preemption
is strictly LRU) while a value of 100 means fully read chunks are
always preempted before other chunks.
Return Codes
------------
`NC_NOERR`
: No error.
3. Groups {#f77_Groups}
=========
NetCDF-4 addedpport for hierarchical groups within netCDF datasets.
Groups are identified with a ncid, which identifies both the open file,
and the group within that file. When a file is opened with NF\_OPEN or
NF\_CREATE, the ncid for the root group of that file is provided. Using
that as a starting point, users can add new groups, or list and navigate
existing groups.
All netCDF calls take a ncid which determines where the call will take
its action. For example, the NF\_DEF\_VAR function takes a ncid as its
first parameter. It will create a variable in whichever group its ncid
refers to. Use the root ncid provided by NF\_CREATE or NF\_OPEN to
create a variable in the root group. Or use NF\_DEF\_GRP to create a
group and use its ncid to define a variable in the new group.
Variable are only visible in the group in which they are defined. The
same applies to attributes. “Global” attributes are defined in whichever
group is refered to by the ncid.
Dimensions are visible in their groups, and all child groups.
Group operations are only permitted on netCDF-4 files - that is, files
created with the HDF5 flag in nf\_create. (see
[NF\_CREATE](#NF_005fCREATE)). Groups are not compatible with the netCDF
classic data model, so files created with the NF\_CLASSIC\_MODEL file
cannot contain groups (except the root group).
3.1 Find a Group ID: NF_INQ_NCID {#f77_NF-INQ-NCID}
----------------------------------
Given an ncid and group name (NULL or "" gets root group), return ncid
of the named group.
Usage
-----
INTEGER FUNCTION NF_INQ_NCID(INTEGER NCID, CHARACTER*(*) NAME, INTEGER GRPID)
`NCID`
: The group id for this operation.
`NAME`
: A character array that holds the name of the desired group. Must be
less then NF\_MAX\_NAME.
`GRPID`
: The ID of the group will go here.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check getting the group by name
retval = nf_inq_ncid(ncid, group_name, grpid_in)
if (retval .ne. nf_noerr) call handle_err(retval)
3.2 Get a List of Groups in a Group: NF_INQ_GRPS {#f77_NF-INQ-GRPS}
--------------------------------------------------
Given a location id, return the number of groups it contains, and an
array of their ncids.
Usage
-----
INTEGER FUNCTION NF_INQ_GRPS(INTEGER NCID, INTEGER NUMGRPS, INTEGER NCIDS)
`NCID`
: The group id for this operation.
`NUMGRPS`
: An integer which will get number of groups in this group.
`NCIDS`
: An array of ints which will receive the IDs of all the groups in
this group.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C What groups are there from the root group?
retval = nf_inq_grps(ncid, ngroups_in, grpids)
if (retval .ne. nf_noerr) call handle_err(retval)
3.3 Find all the Variables in a Group: NF_INQ_VARIDS {#f77_NF-INQ-VARIDS}
------------------------------------------------------
Find all varids for a location.
Usage
-----
INTEGER FUNCTION NF_INQ_VARIDS(INTEGER NCID, INTEGERS VARIDS)
`NCID`
: The group id for this operation.
`VARIDS`
: An already allocated array to store the list of varids. Use
nf\_inq\_nvars to find out how many variables there are. (see
[NF\_INQ Family](#NF_005fINQ-Family)).
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check varids inbgroup.
retval = nf_inq_varidsbgrp_in, nvars, varids_in)
if (retval .ne. nf_noerr) call handle_err(retval)
3.4 Find all Dimensions Visible in a Group: NF_INQ_DIMIDS {#f77_NF-INQ-DIMIDS}
-----------------------------------------------------------
Find all dimids for a location. This finds all dimensions in a group, or
any of its parents.
Usage
-----
INTEGER FUNCTION NF_INQ_DIMIDS(INTEGER NCID, INTEGER NDIMS, INTEGER DIMIDS, INTEGER INCLUDE_PARENTS)
`NCID`
: The group id for this operation.
`NDIMS`
: Returned number of dimensions for this location. If INCLUDE\_PARENTS
is non-zero, number of dimensions visible from this group, which
includes dimensions in parent groups.
`DIMIDS`
: An array of ints when the dimids of the visible dimensions will be
stashed. Use nf\_inq\_ndims to find out how many dims are visible
from this group. (see [NF\_INQ Family](#NF_005fINQ-Family)).
`INCLUDE_PARENTS`
: If zero, only the group specified by NCID will be searched for
dimensions. Otherwise parent groups will be searched too.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check dimids inbgroup.
retval = nf_inq_dimidsbgrp_in, ndims, dimids_in, 0)
if (retval .ne. nf_noerr) call handle_err(retval)
if (ndims .ne. 2 .or. dimids_in(1) .ne. dimids(1) .or.
& dimids_in(2) .ne. dimids(2)) stop 2
3.5 Find the Length of a Group’s Name: NF_INQ_GRPNAME_LE {#f77_NF-INQ-GRPNAME-LE}
------------------------------------------------------------
Given ncid, find length of the full name. (Root group is named "/", with
length 1.)
Usage
-----
INTEGER FUNCTION NF_INQ_GRPNAME_LEN(INTEGER NCID, INTEGER LEN)
`NCID`
: The group id for this operation.
`LEN`
: An integer where the length will be placed.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check the length of the full name.
retval = nf_inq_grpname_len(grpids(1), full_name_len)
if (retval .ne. nf_noerr) call handle_err(retval)
3.6 Find a Group’s Name: NF_INQ_GRPNAME {#f77_NF-INQ-GRPNAME}
-----------------------------------------
Given ncid, find relative name of group. (Root group is named "/").
The name provided by this function is relative to the parent group. For
a full path name for the group is, with all parent groups included,
separated with a forward slash (as in Unix directory names) See
[Find a Group’s Full Name:
NF\_INQ\_GRPNAME\_FULL](#NF_005fINQ_005fGRPNAME_005fFULL).
Usage
-----
INTEGER FUNCTION NF_INQ_GRPNAME(INTEGER NCID, CHARACTER*(*) NAME)
`NCID`
The group id for this operation.
`NAME`
The name of the group will be copied to this character array. The name
will be less than NF\_MAX\_NAME in length.
``
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check the name of the root group.
retval = nf_inq_grpname(ncid, name_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (name_in(1:1) .ne. '/') stop 2
3.7 Find a Group’s Full Name: NF_INQ_GRPNAME_FULL {#f77_NF-INQ-GRPNAME-FULL}
----------------------------------------------------
Given ncid, find complete name of group. (Root group is named "/").
The name provided by this function is a full path name for the group is,
with all parent groups included, separated with a forward slash (as in
Unix directory names). For a name relative to the parent group See
section [Find a Group’s Name:
NF\_INQ\_GRPNAME](#NF_005fINQ_005fGRPNAME).
To find the length of the full name See [Find the Length of a
Group’s Name: NF\_INQ\_GRPNAME\_LEN](#NF_005fINQ_005fGRPNAME_005fLEN).
Usage
-----
INTEGER FUNCTION NF_INQ_GRPNAME_FULL(INTEGER NCID, INTEGER LEN, CHARACTER*(*) NAME)
`NCID`
: The group id for this operation.
`LEN`
: The length of the full group name will go here.
`NAME`
: The name of the group will be copied to this character array.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check the full name.
retval = nf_inq_grpname_full(grpids(1), full_name_len, name_in2)
if (retval .ne. nf_noerr) call handle_err(retval)
3.8 Find a Group’s Parent: NF_INQ_GRP_PARENT {#f77_NF-INQ-GRP-PARENT}
-----------------------------------------------
Given ncid, find the ncid of the parent group.
When used with the root group, this function returns the NF\_ENOGRP
error (since the root group has no parent.)
Usage
-----
INTEGER FUNCTION NF_INQ_GRP_PARENT(INTEGER NCID, INTEGER PARENT_NCID)
`NCID`
: The group id.
`PARENT_NCID`
: The ncid of the parent group will be copied here.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENOGRP`
: No parent group found (i.e. this is the root group).
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check the parent ncid.
retval = nf_inq_grp_parent(grpids(1), grpid_in)
if (retval .ne. nf_noerr) call handle_err(retval)
3.9 Find a Group by Name: NF_INQ_GRP_NCID {#f77_NF-INQ-GRP-NCID}
--------------------------------------------
Given a group name an an ncid, find the ncid of the group id.
Usage
-----
INTEGER FUNCTION NF_INQ_GRP_NCID(INTEGER NCID, CHARACTER GRP_NAME, INTEGER GRP_NCID)
`NCID`
: The group id to look in.
`GRP_NAME`
: The name of the group that should be found.
`GRP_NCID`
: This will get the group id, if it is found.
Return Codes
------------
The following return codes may be returned by this function.
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_EINVAL`
: No name provided or name longer than NF\_MAX\_NAME.
`NF_ENOGRP`
: Named group not found.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_types3.F.
C Go to a child group and find the id of our type.
retval = nf_inq_grp_ncid(ncid, group_name,b_grpid)
if (retval .ne. nf_noerr) call handle_err(retval)
3.10 Find a Group by its Fully-qualified Name: NF_INQ_GRP_FULL_NCID {#f77_NF-INQ-GRP-FULL-NCID}
-----------------------------------------------------------------------
Given a fully qualified group name an an ncid, find the ncid of the
group id.
Usage
-----
INTEGER FUNCTION NF_INQ_GRP_FULL_NCID(INTEGER NCID, CHARACTER FULL_NAME, INTEGER GRP_NCID)
`NCID`
: The group id to look in.
`FULL_NAME`
: The fully-qualified group name.
`GRP_NCID`
: This will get the group id, if it is found.
Return Codes
------------
The following return codes may be returned by this function.
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_EINVAL`
: No name provided or name longer than NF\_MAX\_NAME.
`NF_ENOGRP`
: Named group not found.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_groups.F.
C Check the full name of the root group (also "/").
retval = nf_inq_grpname_full(ncid, full_name_len, name_in)
if (retval .ne. nf_noerr) call handle_err(retval)
3.11 Create a New Group: NF_DEF_GRP {#f77_NF-DEF-GRP}
-------------------------------------
Create a group. Its location id is returned in new\_ncid.
Usage
-----
INTEGER FUNCTION NF_DEF_GRP(INTEGER PARENT_NCID, CHARACTER*(*) NAME,
INTEGER NEW_NCID)
`PARENT_NCID`
: The group id of the parent group.
`NAME`
: The name of the new group, which must be different from the name of
any variable within the same parent group.
`NEW_NCID`
: The ncid of the new group will be placed there.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENAMEINUSE`
: That name is in use. Group names must be unique within a group.
`NF_EMAXNAME`
: Name exceed max length NF\_MAX\_NAME.
`NF_EBADNAME`
: Name contains illegal characters.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag HDF5. (see [NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_EPERM`
: Attempt to write to a read-only file.
`NF_ENOTINDEFINE`
: Not in define mode.
Example
-------
In this exampe rom nf\_test/ftst\_groups.F, a groups is reated, and then
ab-group is created in that group.
C Create the netCDF file.
retval = nf_create(file_name, NF_NETCDF4, ncid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Create a group and abgroup.
retval = nf_def_grp(ncid, group_name, grpid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_def_grp(grpid,b_group_name,b_grpid)
if (retval .ne. nf_noerr) call handle_err(retval)
4. Dimensions {#f77_Dimensions}
=============
4.1 Dimensions Introduction {#f77_Dimensions-Introduction}
---------------------------
Dimensions for a netCDF dataset are defined when it is created, while
the netCDF dataset is in define mode. Additional dimensions may be added
later by reentering define mode. A netCDF dimension has a name and a
length. At most one dimension in a netCDF dataset can have the unlimited
length, which means variables using this dimension can grow along this
dimension.
There is aggested limit (100) to the number of dimensions that can be
defined in a single netCDF dataset. The limit is the value of the
predefined macro NF\_MAX\_DIMS. The purpose of the limit is to make
writing generic applications simpler. They need only provide an array of
NF\_MAX\_DIMS dimensions to handle any netCDF dataset. The
implementation of the netCDF library does not enforce this advisory
maximum, so it is possible to use more dimensions, if necessary, but
netCDF utilities that ame the advisory maximums may not be able to
handle the rlting netCDF datasets.
Ordinarily, the name and length of a dimension are fixed when the
dimension is first defined. The name may be changed later, but the
length of a dimension (other than the unlimited dimension) cannot be
changed without copying all the data to a new netCDF dataset with a
redefined dimension length.
A netCDF dimension in an open netCDF dataset is referred to by a small
integer called a dimension ID. In the FORTRAN interface, dimension IDs
are 1, 2, 3, ..., in the order in which the dimensions were defined.
Operationspported on dimensions are:
- Create a dimension, given its name and length.
- Get a dimension ID from its name.
- Get a dimension’s name and length from its ID.
- Rename a dimension.
4.2 NF_DEF_DIM {#f77_NF-DEF-DIM}
----------------
The function NF\_DEF\_DIM adds a new dimension to an open netCDF dataset
in define mode. It returns (as an argument) a dimension ID, given the
netCDF ID, the dimension name, and the dimension length. At most one
unlimited length dimension, called the record dimension, may be defined
for each netCDF dataset.
Usage
-----
INTEGER FUNCTION NF_DEF_DIM (INTEGER NCID, CHARACTER*(*) NAME,
INTEGER LEN, INTEGER dimid)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`NAME`
: Dimension name.
`LEN`
: Length of dimension; that is, number of values for this dimension as
an index to variables that use it. This should be either a positive
integer or the predefined constant NF\_UNLIMITED.
`dimid`
: Returned dimension ID.
Errors
------
NF\_DEF\_DIM returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The netCDF dataset is not in definition mode.
- The specified dimension name is the name of another existing
dimension.
- The specified length is not greater than zero.
- The specified length is unlimited, but there is already an unlimited
length dimension defined for this netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_DEF\_DIM to create a dimension named lat of
length 18 and a unlimited dimension named rec in a new netCDF dataset
named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, LATID, RECID
...
STATUS = NF_CREATE('foo.nc', NF_NOCLOBBER, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_DEF_DIM(NCID, 'lat', 18, LATID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_DEF_DIM(NCID, 'rec', NF_UNLIMITED, RECID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
4.3 NF_INQ_DIMID {#f77_NF-INQ-DIMID}
------------------
The function NF\_INQ\_DIMID returns (as an argument) the ID of a netCDF
dimension, given the name of the dimension. If ndims is the number of
dimensions defined for a netCDF dataset, each dimension has an ID
between 1 and ndims.
Usage
-----
INTEGER FUNCTION NF_INQ_DIMID (INTEGER NCID, CHARACTER*(*) NAME,
INTEGER dimid)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`NAME`
: Dimension name.
`dimid`
: Returned dimension ID.
Errors
------
NF\_INQ\_DIMID returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The name that was specified is not the name of a dimension in the
netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_INQ\_DIMID to determine the dimension ID of
a dimension named lat, amed to have been defined previously in an
existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, LATID
...
STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_DIMID(NCID, 'lat', LATID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
4.4 NF_INQ_DIM Family {#f77_NF-INQ-DIM-Family}
-----------------------
This family of functions returns information about a netCDF dimension.
Information about a dimension includes its name and its length. The
length for the unlimited dimension, if any, is the number of records
written so far.
The functions in this family include NF\_INQ\_DIM, NF\_INQ\_DIMNAME, and
NF\_INQ\_DIMLEN. The function NF\_INQ\_DIM returns all the information
about a dimension; the other functions each return just one item of
information.
Usage
-----
INTEGER FUNCTION NF_INQ_DIM (INTEGER NCID, INTEGER DIMID,
CHARACTER*(*) name, INTEGER len)
INTEGER FUNCTION NF_INQ_DIMNAME (INTEGER NCID, INTEGER DIMID,
CHARACTER*(*) name)
INTEGER FUNCTION NF_INQ_DIMLEN (INTEGER NCID, INTEGER DIMID,
INTEGER len)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`DIMID`
: Dimension ID, from a previous call to NF\_INQ\_DIMID or
NF\_DEF\_DIM.
`NAME`
: Returned dimension name. The caller must allocate space for the
returned name. The maximum possible length, in characters, of a
dimension name is given by the predefined constant NF\_MAX\_NAME.
`len`
: Returned length of dimension. For the unlimited dimension, this is
the current maximum value used for writing any variables with this
dimension, that is the maximum record number.
Errors
------
These functions return the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The dimension ID is invalid for the specified netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_INQ\_DIM to determine the length of a
dimension named lat, and the name and current maximum length of the
unlimited dimension for an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, LATID, LATLEN, RECID, NRECS
CHARACTER*(NF_MAX_NAME) LATNAM, RECNAM
...
STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
! get ID of unlimited dimension
STATUS = NF_INQ_UNLIMDIM(NCID, RECID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_DIMID(NCID, 'lat', LATID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
! get lat length
STATUS = NF_INQ_DIMLEN(NCID, LATID, LATLEN)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
! get unlimited dimension name and current length
STATUS = NF_INQ_DIM(NCID, RECID, RECNAME, NRECS)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
4.5 NF_RENAME_DIM {#f77_NF-RENAME-DIM}
-------------------
The function NF\_RENAME\_DIM renames an existing dimension in a netCDF
dataset open for writing. If the new name is longer than the old name,
the netCDF dataset must be in define mode. You cannot rename a dimension
to have the same name as another dimension.
Usage
-----
INTEGER FUNCTION NF_RENAME_DIM (INTEGER NCID, INTEGER DIMID,
CHARACTER*(*) NAME)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`DIMID`
: Dimension ID, from a previous call to NF\_INQ\_DIMID or
NF\_DEF\_DIM.
`NAME`
: New dimension name.
Errors
------
NF\_RENAME\_DIM returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The new name is the name of another dimension.
- The dimension ID is invalid for the specified netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
- The new name is longer than the old name and the netCDF dataset is
not in define mode.
Example
-------
Here is an example using NF\_RENAME\_DIM to rename the dimension lat to
latitude in an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, LATID
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! put in define mode to rename dimension
STATUS = NF_REDEF(NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_DIMID(NCID, 'lat', LATID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_RENAME_DIM(NCID, LATID, 'latitude')
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
! leave define mode
STATUS = NF_ENDDEF(NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
5. User Defined Data Types {#f77_User-Defined-Data-Types}
==========================
5.1 User Defined Types Introduction {#f77_User-Defined-Types-Introduction}
-----------------------------------
NetCDF-4 has added support for four different user defined data types.
`compound type`
: Like a C struct, a compound type is a collection of types, including
other user defined types, in one package.
`variable length array type`
: The variable length array may be used to store ragged arrays.
`opaque type`
: This type has only a size per element, and no other type
information.
`enum type`
: Like an enumeration in C, this type lets you assign text values to
integer values, and store the integer values.
Users may construct user defined type with the various NF\_DEF\_\*
functions described in this. They may learn about user defined
types by using the NF\_INQ\_ functions defined in this.
Once types are constructed, define variables of the new type with
NF\_DEF\_VAR (see [Create a Variable:
`NF_DEF_VAR`](#NF_005fDEF_005fVAR)). Write to them with NF\_PUT\_VAR1,
NF\_PUT\_VAR, NF\_PUT\_VARA, or NF\_PUT\_VARS (see
[Variables](#Variables)). Read data of user-defined type with
NF\_GET\_VAR1, NF\_GET\_VAR, NF\_GET\_VARA, or NF\_GET\_VARS (see
section [Variables](#Variables)).
Create attributes of the new type with NF\_PUT\_ATT (see
[NF\_PUT\_ATT\_ type](#NF_005fPUT_005fATT_005f-type)). Read attributes
of the new type with NF\_GET\_ATT (see [NF\_GET\_ATT\_
type](#NF_005fGET_005fATT_005f-type)).
5.2 Learn the IDs of All Types in Group: NF_INQ_TYPEIDS {#f77_NF-INQ-TYPEIDS}
---------------------------------------------------------
Learn the number of types defined in a group, and their IDs.
Usage
-----
INTEGER FUNCTION NF_INQ_TYPEIDS(INTEGER NCID, INTEGER NTYPES,
INTEGER TYPEIDS)
`NCID`
: The group id.
`NTYPES`
: A pointer to int which will get the number of types defined in the
group. If NULL, ignored.
`TYPEIDS`
: A pointer to an int array which will get the typeids. If NULL,
ignored.
Errors
------
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
Example
-------
The following example is from the test program nf\_test/ftst\_vars3.F.
retval = nf_inq_typeids(ncid, num_types, typeids)
if (retval .ne. nf_noerr) call handle_err(retval)
5.3 Find a Typeid from Group and Name: NF_INQ_TYPEID {#f77_NF-INQ-TYPEID}
------------------------------------------------------
Given a group ID and a type name, find the ID of the type. If the type
is not found in the group, then the parents are searched. If still not
found, the entire file is searched.
Usage
-----
INTEGER FUNCTION NF_INQ_TYPEID(INTEGER NCID, CHARACTER NAME, NF_TYPE TYPEIDP)
`NCID`
: The group id.
`NAME`
: The name of a type.
`TYPEIDP`
: The typeid of the named type (if found).
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad ncid.
`NF_EBADTYPE`
: Can’t find type.
Example
-------
The following example is from nf\_test/ftst\_types3.F:
C Go to a child group and find the id of our type.
retval = nf_inq_grp_ncid(ncid, group_name,b_grpid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_inq_typeidb_grpid, type_name, typeid_in)
if (retval .ne. nf_noerr) call handle_err(retval)
5.4 Learn About a User Defined Type: NF_INQ_TYPE {#f77_NF-INQ-TYPE}
--------------------------------------------------
Given an ncid and a typeid, get the information about a type. This
function will work on any type, including atomic and any user defined
type, whether compound, opaque, enumeration, or variable length array.
For even more information about a user defined type [Learn About a User
Defined Type: NF\_INQ\_USER\_TYPE](#NF_005fINQ_005fUSER_005fTYPE).
Usage
-----
INTEGER FUNCTION NF_INQ_TYPE(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER SIZE)
`NCID`
: The ncid for the group containing the type (ignored for atomic
types).
`XTYPE`
: The typeid for this type, as returned by NF\_DEF\_COMPOUND,
NF\_DEF\_OPAQUE, NF\_DEF\_ENUM, NF\_DEF\_VLEN, or NF\_INQ\_VAR, or
as found in netcdf.inc in the list of atomic types (NF\_CHAR,
NF\_INT, etc.).
`NAME`
: The name of the user defined type will be copied here. It will be
NF\_MAX\_NAME bytes or less. For atomic types, the type name from
CDL will be given.
`SIZEP`
: The (in-memory) size of the type (in bytes) will be copied here.
VLEN type size is the size of one vlen sturture (i.e. the sice of
nc\_vlen\_t). String size is returned as the size of one C character
pointer.
Return Codes
------------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad typeid.
`NF_ENOTNC4`
: Seeking a user-defined type in a netCDF-3 file.
`NF_ESTRICTNC3`
: Seeking a user-defined type in a netCDF-4 file for which classic
model has been turned on.
`NF_EBADGRPID`
: Bad group ID in ncid.
`NF_EBADID`
: Type ID not found.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from the test program nf\_test/ftst\_vars3.F, and it
uses all the possible inquiry functions on an enum type.
C Check the enum type.
retval = NF_INQ_TYPEIDS(ncid, num_types, typeids)
if (retval .ne. nf_noerr) call handle_err(retval)
if (num_types .ne. MAX_TYPES) stop 2
retval = nf_inq_enum(ncid, typeids(1), type_name, base_type,
& base_size, num_members)
if (retval .ne. nf_noerr) call handle_err(retval)
if (base_type .ne. NF_INT .or. num_members .ne. 2) stop 2
retval = nf_inq_enum_member(ncid, typeids(1), 1, member_name,
& member_value)
if (retval .ne. nf_noerr) call handle_err(retval)
if (member_name(1:len(one_name)) .ne. one_name) stop 2
5.5 Learn About a User Defined Type: NF_INQ_USER_TYPE {#f77_NF-INQ-USER-TYPE}
--------------------------------------------------------
Given an ncid and a typeid, get the information about a user defined
type. This function will work on any user defined type, whether
compound, opaque, enumeration, or variable length array.
Usage
-----
INTEGER FUNCTION NF_INQ_USER_TYPE(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER SIZE, INTEGER BASE_NF_TYPE,
INTEGER NFIELDS, INTEGER CLASS)
`NCID`
: The ncid for the group containing the user defined type.
`XTYPE`
: The typeid for this type, as returned by NF\_DEF\_COMPOUND,
NF\_DEF\_OPAQUE, NF\_DEF\_ENUM, NF\_DEF\_VLEN, or NF\_INQ\_VAR.
`NAME`
: The name of the user defined type will be copied here. It will be
NF\_MAX\_NAME bytes or less.
`SIZE`
: The (in-memory) size of the user defined type will be copied here.
`BASE_NF_TYPE`
: The base typeid will be copied here for vlen and enum types.
`NFIELDS`
: The number of fields will be copied here for enum and compound
types.
`CLASS`
: The class of the user defined type, NF\_VLEN, NF\_OPAQUE, NF\_ENUM,
or NF\_COMPOUND, will be copied here.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad typeid.
`NF_EBADFIELDID`
: Bad fieldid.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_types2.F.
C Check the type.
retval = nf_inq_user_type(ncid, typeids(1), name_in, size_in,
& base_type_in, nfields_in, class_in)
if (retval .ne. nf_noerr) call handle_err(retval)
5.6 Compound Types Introduction {#f77_Compound-Types-Introduction}
-------------------------------
NetCDF-4 addedpport for compound types, which allow users to
construct a new type - a combination of other types, like a C struct.
Compound types are notpported in classic or 64-bit offset format
files.
To write data in a compound type, first use nf\_def\_compound to create
the type, multiple calls to nf\_insert\_compound to add to the compound
type, and then write data with the appropriate nf\_put\_var1,
nf\_put\_vara, nf\_put\_vars, or nf\_put\_varm call.
To read data written in a compound type, you must know its structure.
Use the NF\_INQ\_COMPOUND functions to learn about the compound type.
In Fortran a character buffer must be used for the compound data. The
user must read the data from within that buffer in the same way that the
C compiler which compiled netCDF would store the structure.
The use of compound types introduces challenges and portability ies
for Fortran users.
### 5.6.1 Creating a Compound Type: NF_DEF_COMPOUND {#f77_NF-DEF-COMPOUND}
Create a compound type. Provide an ncid, a name, and a total size (in
bytes) of one element of the completed compound type.
After calling this function, fill out the type with repeated calls to
NF\_INSERT\_COMPOUND (see [Inserting a Field into a Compound
Type: NF\_INSERT\_COMPOUND](#NF_005fINSERT_005fCOMPOUND)). Call
NF\_INSERT\_COMPOUND once for each field you wish to insert into the
compound type.
Note that there does not seem to be a way to readch types into
structures in Fortran 90 (and there are no structures in Fortran 77).
Fortran users may use character buffers to read and write compound
types.
Usage
-----
INTEGER FUNCTION NF_DEF_COMPOUND(INTEGER NCID, INTEGER SIZE,
CHARACTER*(*) NAME, INTEGER TYPEIDP)
`NCID`
: The groupid where this compound type will be created.
`SIZE`
: The size, in bytes, of the compound type.
`NAME`
: The name of the new compound type.
`TYPEIDP`
: The typeid of the new type will be placed here.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENAMEINUSE`
: That name is in use. Compound type names must be unique in the data
file.
`NF_EMAXNAME`
: Name exceeds max length NF\_MAX\_NAME.
`NF_EBADNAME`
: Name contains illegal characters.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag NF\_NETCDF4. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_EPERM`
: Attempt to write to a read-only file.
`NF_ENOTINDEFINE`
: Not in define mode.
Example
-------
This example is from nf\_test/ftst\_types2.F.
C Define a compound type.
retval = nf_def_compound(ncid, cmp_size, type_name,
& cmp_typeid)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.6.2 Inserting a Field into a Compound Type: NF_INSERT_COMPOUND {#f77_NF-INSERT-COMPOUND}
Insert a named field into a compound type.
Usage
-----
INTEGER FUNTION NF_INSERT_COMPOUND(INTEGER TYPEID, CHARACTER*(*) NAME, INTEGER OFFSET,
INTEGER FIELD_TYPEID)
`TYPEID`
: The typeid for this compound type, as returned by NF\_DEF\_COMPOUND,
or NF\_INQ\_VAR.
`NAME`
: The name of the new field.
`OFFSET`
: Offset in byte from the beginning of the compound type for this
field.
`FIELD_TYPEID`
: The type of the field to be inserted.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENAMEINUSE`
: That name is in use. Field names must be unique within a compound
type.
`NF_EMAXNAME`
: Name exceed max length NF\_MAX\_NAME.
`NF_EBADNAME`
: Name contains illegal characters.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag NF\_NETCDF4. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_ENOTINDEFINE`
: Not in define mode.
Example
-------
This example is from nf\_test/ftst\_types.F.
C Define a compound type.
retval = nf_def_compound(ncid, WIND_T_SIZE, type_name,
& wind_typeid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_insert_compound(ncid, wind_typeid, u_name, 0, NF_INT)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_insert_compound(ncid, wind_typeid, v_name, 4, NF_INT)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.6.3 Inserting an Array Field into a Compound Type: NF_INSERT_ARRAY_COMPOUND {#f77_NF-INSERT-ARRAY-COMPOUND}
Insert a named array field into a compound type.
Usage
-----
INTEGER FUNCTION NF_INSERT_ARRAY_COMPOUND(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER OFFSET, INTEGER FIELD_TYPEID,
INTEGER NDIMS, INTEGER DIM_SIZES)
`NCID`
: The ID of the file that contains the array type and the compound
type.
`XTYPE`
: The typeid for this compound type, as returned by nf\_def\_compound,
or nf\_inq\_var.
`NAME`
: The name of the new field.
`OFFSET`
: Offset in byte from the beginning of the compound type for this
field.
`FIELD_TYPEID`
: The base type of the array to be inserted.
`NDIMS`
: The number of dimensions for the array to be inserted.
`DIM_SIZES`
: An array containing the sizes of each dimension.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENAMEINUSE`
: That name is in use. Field names must be unique within a compound
type.
`NF_EMAXNAME`
: Name exceed max length NF\_MAX\_NAME.
`NF_EBADNAME`
: Name contains illegal characters.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag NF\_NETCDF4. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_ENOTINDEFINE`
: Not in define mode.
`NF_ETYPEDEFINED`
: Attempt to change type that has already been committed. The first
time the file leaves define mode, all defined types are committed,
and can’t be changed. If you wish to add an array to a compound
type, you must do so before the compound type is committed.
Example
-------
This example is from nf\_test/ftst\_types2.F.
C Define a compound type.
retval = nf_def_compound(ncid, cmp_size, type_name,
& cmp_typeid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Include an array.
dim_sizes(1) = NX
dim_sizes(2) = NY
retval = nf_insert_array_compound(ncid, cmp_typeid, ary_name, 0,
& NF_INT, NDIMS, dim_sizes)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.6.4 Learn About a Compound Type: NF_INQ_COMPOUND {#f77_NF-INQ-COMPOUND}
Get the number of fields, length in bytes, and name of a compound type.
In addtion to the NF\_INQ\_COMPOUND function, three additional functions
are provided which get only the name, size, and number of fields.
Usage
-----
INTEGER FUNCTION NF_INQ_COMPOUND(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER SIZEP, INTEGER NFIELDSP)
INTEGER FUNCTION NF_INQ_COMPOUND_NAME(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME)
INTEGER FUNCTION NF_INQ_COMPOUND_SIZE(INTEGER NCID, INTEGER XTYPE,
INTEGER SIZEP)
INTEGER FUNCTION NF_INQ_COMPOUND_NFIELDS(INTEGER NCID, INTEGER XTYPE,
INTEGER NFIELDSP)
`NCID`
: The ID of any group in the file that contains the compound type.
`XTYPE`
: The typeid for this compound type, as returned by NF\_DEF\_COMPOUND,
or NF\_INQ\_VAR.
`NAME`
: Character array which will get the name of the compound type. It
will have a maximum length of NF\_MAX\_NAME.
`SIZEP`
: The size of the compound type in bytes will be put here.
`NFIELDSP`
: The number of fields in the compound type will be placed here.
Return Codes
------------
`NF_NOERR`
: No error.
`NF_EBADID`
: Couldn’t find this ncid.
`NF_ENOTNC4`
: Not a netCDF-4/HDF5 file.
`NF_ESTRICTNC3`
: A netCDF-4/HDF5 file, but with CLASSIC\_MODEL. No user defined types
are allowed in the classic model.
`NF_EBADTYPE`
: This type not a compound type.
`NF_EBADTYPEID`
: Bad type id.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_types.F.
C Check it differently.
retval = nf_inq_compound(ncid, typeids(1), name_in, size_in,
& nfields_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (name_in(1:len(type_name)) .ne. type_name .or.
& size_in .ne. WIND_T_SIZE .or. nfields_in .ne. 2) stop 2
C Check it one piece at a time.
retval = nf_inq_compound_nfields(ncid, typeids(1), nfields_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (nfields_in .ne. 2) stop 2
retval = nf_inq_compound_size(ncid, typeids(1), size_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (size_in .ne. WIND_T_SIZE) stop 2
retval = nf_inq_compound_name(ncid, typeids(1), name_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (name_in(1:len(type_name)) .ne. type_name) stop 2
### 5.6.5 Learn About a Field of a Compound Type: NF_INQ_COMPOUND_FIELD {#f77_NF-INQ-COMPOUND-FIELD}
Get information about one of the fields of a compound type.
Usage
-----
INTEGER FUNCTION NF_INQ_COMPOUND_FIELD(INTEGER NCID, INTEGER XTYPE,
INTEGER FIELDID, CHARACTER*(*) NAME, INTEGER OFFSETP,
INTEGER FIELD_TYPEIDP, INTEGER NDIMSP, INTEGER DIM_SIZESP)
INTEGER FUNCTION NF_INQ_COMPOUND_FIELDNAME(INTEGER TYPEID,
INTEGER FIELDID, CHARACTER*(*) NAME)
INTEGER FUNCTION NF_INQ_COMPOUND_FIELDINDEX(INTEGER TYPEID,
CHARACTER*(*) NAME, INTEGER FIELDIDP)
INTEGER FUNCTION NF_INQ_COMPOUND_FIELDOFFSET(INTEGER TYPEID,
INTEGER FIELDID, INTEGER OFFSETP)
INTEGER FUNCTION NF_INQ_COMPOUND_FIELDTYPE(INTEGER TYPEID,
INTEGER FIELDID, INTEGER FIELD_TYPEIDP)
INTEGER FUNCTION NF_INQ_COMPOUND_FIELDNDIMS(INTEGER NCID,
INTEGER XTYPE, INTEGER FIELDID, INTEGER NDIMSP)
INTEGER FUNCTION NF_INQ_COMPOUND_FIELDDIM_SIZES(INTEGER NCID,
INTEGER XTYPE, INTEGER FIELDID, INTEGER DIM_SIZES)
`NCID`
: The groupid where this compound type exists.
`XTYPE`
: The typeid for this compound type, as returned by NF\_DEF\_COMPOUND,
or NF\_INQ\_VAR.
`FIELDID`
: A one-based index number specifying a field in the compound type.
`NAME`
: A character array which will get the name of the field. The name
will be NF\_MAX\_NAME characters, at most.
`OFFSETP`
: An integer which will get the offset of the field.
`FIELD_TYPEID`
: An integer which will get the typeid of the field.
`NDIMSP`
: An integer which will get the number of dimensions of the field.
`DIM_SIZESP`
: An integer array which will get the dimension sizes of the field.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad type id.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/fst\_types.F.
~~~~
C Check the first field of the compound type.
retval = nf_inq_compound_field(ncid, typeids(1), 1, name_in,
& offset_in, field_typeid_in, ndims_in, dim_sizes_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (name_in(1:len(u_name)) .ne. u_name .or. offset_in .ne. 0 .or.
& field_typeid_in .ne. NF_INT .or. ndims_in .ne. 0) stop 2
retval = nf_inq_compound_fieldname(ncid, typeids(1), 1, name_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (name_in(1:len(u_name)) .ne. u_name) stop 2
retval = nf_inq_compound_fieldoffset(ncid, typeids(1), 1,
& offset_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (offset_in .ne. 0) stop 2
retval = nf_inq_compound_fieldtype(ncid, typeids(1), 1,
& field_typeid_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (field_typeid_in .ne. NF_INT) stop 2
retval = nf_inq_compound_fieldndims(ncid, typeids(1), 1,
& ndims_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (ndims_in .ne. 0) stop 2
~~~~
5.7 Variable Length Array Introduction
--------------------------------------
NetCDF-4 addedpport for a variable length array type. This is not
supported in classic or 64-bit offset files, or in netCDF-4 files which
were created with the NF\_CLASSIC\_MODEL flag.
A variable length array is represented in C as a structure from HDF5,
the nf\_vlen\_t structure. It contains a len member, which contains the
length of that array, and a pointer to the array.
So an array of VLEN in C is an array of nc\_vlen\_t structures. The only
way to handle this in Fortran is with a character buffer sized correctly
for the platform.
The extra access functions NF\_GET\_VLEN\_ELEMENT and
NF\_PUT\_VLEN\_ELEMENT to get and put one VLEN element. (That is, one
array of variable length.) When calling the put, the data are not copied
from the source. When calling the get the data are copied from VLEN
allocated memory, which must still be freed (see below).
VLEN arrays are handled differently with respect to allocation of
memory. Generally, when reading data, it is up to the user to malloc
(andbsequently free) the memory needed to hold the data. It is up to
the user to ere that enough memory is allocated.
With VLENs, this is impossible. The user cannot know the size of an
array of VLEN until after reading the array. Therefore when reading VLEN
arrays, the netCDF library will allocate the memory for the data within
each VLEN.
It is up to the user, however, to eventually free this memory. This is
not just a matter of one call to free, with the pointer to the array of
VLENs; each VLEN contains a pointer which must be freed.
Compression is permitted but may not be effective for VLEN data, because
the compression is applied to the nc\_vlen\_t structures, rather than
the actual data.
### 5.7.1 Define a Variable Length Array (VLEN): NF\_DEF\_VLEN
Use this function to define a variable length array type.
Usage
-----
INTEGER FUNCTION NF_DEF_VLEN(INTEGER NCID, CHARACTER*(*) NAME,
INTEGER BASE_TYPEID, INTEGER XTYPEP)
`NCID`
: The ncid of the file to create the VLEN type in.
`NAME`
: A name for the VLEN type.
`BASE_TYPEID`
: The typeid of the base type of the VLEN. For example, for a VLEN of
shorts, the base type is NF\_SHORT. This can be a user defined type.
`XTYPEP`
: The typeid of the new VLEN type will be set here.
Errors
------
`NF_NOERR`
: No error.
`NF_EMAXNAME`
: NF\_MAX\_NAME exceeded.
`NF_ENAMEINUSE`
: Name is already in use.
`NF_EBADNAME`
: Attribute or variable name contains illegal characters.
`NF_EBADID`
: ncid invalid.
`NF_EBADGRPID`
: Group ID part of ncid was invalid.
`NF_EINVAL`
: Size is invalid.
`NF_ENOMEM`
: Out of memory.
Example
-------
This example is from nf\_test/ftst\_vars4.F.
C Create the vlen type.
retval = nf_def_vlen(ncid, vlen_type_name, nf_int, vlen_typeid)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.7.2 Learning about a Variable Length Array (VLEN) Type: NF\_INQ\_VLEN
Use this type to learn about a vlen.
Usage
-----
INTEGER FUNCTION NF_INQ_VLEN(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER DATUM_SIZEP, INTEGER
BASE_NF_TYPEP)
`NCID`
: The ncid of the file that contains the VLEN type.
`XTYPE`
: The type of the VLEN to inquire about.
`NAME`
: The name of the VLEN type. The name will be NF\_MAX\_NAME characters
or less.
`DATUM_SIZEP`
: A pointer to a size\_t, this will get the size of one element of
this vlen.
`BASE_NF_TYPEP`
: An integer that will get the type of the VLEN base type. (In other
words, what type is this a VLEN of?)
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPE`
: Can’t find the typeid.
`NF_EBADID`
: ncid invalid.
`NF_EBADGRPID`
: Group ID part of ncid was invalid.
Example
-------
This example is from nf\_test/ftst\_vars4.F.
C Use nf_inq_vlen and makere we get the same answers as we did
C with nf_inq_user_type.
retval = nf_inq_vlen(ncid, typeids(1), type_name, base_size,
& base_type)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.7.3 Releasing Memory for a Variable Length Array (VLEN) Type: NF\_FREE\_VLEN
When a VLEN is read into user memory from the file, the HDF5 library
performs memory allocations for each of the variable length arrays
contained within the VLEN structure. This memory must be freed by the
user to avoid memory leaks.
This violates the normal netCDF expectation that the user is responsible
for all memory allocation. But, with VLEN arrays, the underlying HDF5
library allocates the memory for the user, and the user is responsible
for deallocating that memory.
Usage
-----
INTEGER FUNCTION NF_FREE_VLEN(CHARACTER VL);
`VL`
: The variable length array structure which is to be freed.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPE`
: Can’t find the typeid.
Example
-------
### 5.7.4 Set a Variable Length Array with NF\_PUT\_VLEN\_ELEMENT
Use this to set the element of the (potentially) n-dimensional array of
VLEN. That is, this sets the data in one variable length array.
Usage
-----
INTEGER FUNCTION NF_PUT_VLEN_ELEMENT(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) VLEN_ELEMENT, INTEGER LEN, DATA)
`NCID`
: The ncid of the file that contains the VLEN type.
`XTYPE`
: The type of the VLEN.
`VLEN_ELEMENT`
: The VLEN element to be set.
`LEN`
: The number of entries in this array.
`DATA`
: The data to be stored. Must match the base type of this VLEN.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPE`
: Can’t find the typeid.
`NF_EBADID`
: ncid invalid.
`NF_EBADGRPID`
: Group ID part of ncid was invalid.
Example
-------
This example is from nf\_test/ftst\_vars4.F.
C Set up the vlen with this helper function, since F77 can't deal
C with pointers.
retval = nf_put_vlen_element(ncid, vlen_typeid, vlen,
& vlen_len, data1)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.7.5 Set a Variable Length Array with NF\_GET\_VLEN\_ELEMENT
Use this to set the element of the (potentially) n-dimensional array of
VLEN. That is, this sets the data in one variable length array.
Usage
-----
INTEGER FUNCTION NF_GET_VLEN_ELEMENT(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) VLEN_ELEMENT, INTEGER LEN, DATA)
`NCID`
: The ncid of the file that contains the VLEN type.
`XTYPE`
: The type of the VLEN.
`VLEN_ELEMENT`
: The VLEN element to be set.
`LEN`
: This will be set to the number of entries in this array.
`DATA`
: The data will be copied here. Sufficient storage must be available
or bad things will happen to you.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPE`
: Can’t find the typeid.
`NF_EBADID`
: ncid invalid.
`NF_EBADGRPID`
: Group ID part of ncid was invalid.
Example
-------
This example is from nf\_test/ftst\_vars4.F.
C Read the vlen attribute.
retval = nf_get_att(ncid, NF_GLOBAL, 'att1', vlen_in)
if (retval .ne. nf_noerr) call handle_err(retval)
C Get the data from the vlen we just read.
retval = nf_get_vlen_element(ncid, vlen_typeid, vlen_in,
& vlen_len_in, data1_in)
if (retval .ne. nf_noerr) call handle_err(retval)
5.8 Opaque Type Introduction
----------------------------
NetCDF-4 addedpport for the opaque type. This is notpported in
classic or 64-bit offset files.
The opaque type is a type which is a collection of objects of a known
size. (And each object is the same size). Nothing is known to netCDF
about the contents of these blobs of data, except their size in bytes,
and the name of the type.
To use an opaque type, first define it with [Creating Opaque Types:
NF\_DEF\_OPAQUE](#NF_005fDEF_005fOPAQUE). If encountering an enum type
in a new data file, use [Learn About an Opaque Type:
NF\_INQ\_OPAQUE](#NF_005fINQ_005fOPAQUE) to learn its name and size.
### 5.8.1 Creating Opaque Types: NF\_DEF\_OPAQUE
Create an opaque type. Provide a size and a name.
Usage
-----
INTEGER FUNCTION NF_DEF_OPAQUE(INTEGER NCID, INTEGER SIZE,
CHARACTER*(*) NAME, INTEGER TYPEIDP)
`NCID`
: The groupid where the type will be created. The type may be used
anywhere in the file, no matter what group it is in.
`SIZE`
: The size of each opaque object.
`NAME`
: The name for this type. Must be shorter than NF\_MAX\_NAME.
`TYPEIDP`
: Pointer where the new typeid for this type is returned. Use this
typeid when defining variables of this type with [Create a Variable:
`NF_DEF_VAR`](#NF_005fDEF_005fVAR).
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad typeid.
`NF_EBADFIELDID`
: Bad fieldid.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_vars3.F.
C Create the opaque type.
retval = nf_def_opaque(ncid, opaque_size, opaque_type_name,
& opaque_typeid)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.8.2 Learn About an Opaque Type: NF\_INQ\_OPAQUE
Given a typeid, get the information about an opaque type.
Usage
-----
INTEGER FUNCTION NF_INQ_OPAQUE(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER SIZEP)
`NCID`
: The ncid for the group containing the opaque type.
`XTYPE`
: The typeid for this opaque type, as returned by NF\_DEF\_COMPOUND,
or NF\_INQ\_VAR.
`NAME`
: The name of the opaque type will be copied here. It will be
NF\_MAX\_NAME bytes or less.
`SIZEP`
: The size of the opaque type will be copied here.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad typeid.
`NF_EBADFIELDID`
: Bad fieldid.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_vars3.F.
C Use nf_inq_opaque and makere we get the same answers as we did
C with nf_inq_user_type.
retval = nf_inq_opaque(ncid, typeids(2), type_name, base_size)
if (retval .ne. nf_noerr) call handle_err(retval)
5.9 Enum Type Introduction
--------------------------
NetCDF-4 addedpport for the enum type. This is notpported in
classic or 64-bit offset files.
### 5.9.1 Creating a Enum Type: NF\_DEF\_ENUM
Create an enum type. Provide an ncid, a name, and a base integer type.
After calling this function, fill out the type with repeated calls to
NF\_INSERT\_ENUM (see [Inserting a Field into a Enum Type:
NF\_INSERT\_ENUM](#NF_005fINSERT_005fENUM)). Call NF\_INSERT\_ENUM once
for each value you wish to make part of the enumeration.
Usage
-----
INTEGER FUNCTION NF_DEF_ENUM(INTEGER NCID, INTEGER BASE_TYPEID,
CHARACTER*(*) NAME, INTEGER TYPEIDP)
`NCID`
: The groupid where this compound type will be created.
`BASE_TYPEID`
: The base integer type for this enum. Must be one of: NF\_BYTE,
NF\_UBYTE, NF\_SHORT, NF\_USHORT, NF\_INT, NF\_UINT, NF\_INT64,
NF\_UINT64.
`NAME`
: The name of the new enum type.
`TYPEIDP`
: The typeid of the new type will be placed here.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENAMEINUSE`
: That name is in use. Compound type names must be unique in the data
file.
`NF_EMAXNAME`
: Name exceeds max length NF\_MAX\_NAME.
`NF_EBADNAME`
: Name contains illegal characters.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag NF\_NETCDF4. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_EPERM`
: Attempt to write to a read-only file.
`NF_ENOTINDEFINE`
: Not in define mode.
This example is from nf\_test/ftst\_vars3.F.
C Create the enum type.
retval = nf_def_enum(ncid, NF_INT, enum_type_name, enum_typeid)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.9.2 Inserting a Field into a Enum Type: NF\_INSERT\_ENUM
Insert a named member into a enum type.
Usage
-----
INTEGER FUNCTION NF_INSERT_ENUM(INTEGER NCID, INTEGER XTYPE,
CHARACTER IDENTIFIER, INTEGER VALUE)
`NCID`
: The ncid of the group which contains the type.
`TYPEID`
: The typeid for this enum type, as returned by nf\_def\_enum, or
nf\_inq\_var.
`IDENTIFIER`
: The identifier of the new member.
`VALUE`
: The value that is to be associated with this member.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADID`
: Bad group id.
`NF_ENAMEINUSE`
: That name is in use. Field names must be unique within a enum type.
`NF_EMAXNAME`
: Name exceed max length NF\_MAX\_NAME.
`NF_EBADNAME`
: Name contains illegal characters.
`NF_ENOTNC4`
: Attempting a netCDF-4 operation on a netCDF-3 file. NetCDF-4
operations can only be performed on files defined with a create mode
which includes flag NF\_NETCDF4. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_ESTRICTNC3`
: This file was created with the strict netcdf-3 flag, therefore
netcdf-4 operations are not allowed. (see
[NF\_OPEN](#NF_005fOPEN)).
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_ENOTINDEFINE`
: Not in define mode.
Example
-------
This example is from nf\_test/ftst\_vars3.F.
one = 1
zero = 0
retval = nf_insert_enum(ncid, enum_typeid, zero_name, zero)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_insert_enum(ncid, enum_typeid, one_name, one)
if (retval .ne. nf_noerr) call handle_err(retval)
### 5.9.3 Learn About a Enum Type: NF\_INQ\_ENUM
Get information about a user-defined enumeration type.
Usage
-----
INTEGER FUNCTION NF_INQ_ENUM(INTEGER NCID, INTEGER XTYPE,
CHARACTER*(*) NAME, INTEGER BASE_NF_TYPE, INTEGER BASE_SIZE,
INTEGER NUM_MEMBERS)
`NCID`
: The group ID of the group which holds the enum type.
`XTYPE`
: The typeid for this enum type, as returned by NF\_DEF\_ENUM, or
NF\_INQ\_VAR.
`NAME`
: Character array which will get the name. It will have a maximum
length of NF\_MAX\_NAME.
`BASE_NF_TYPE`
: An integer which will get the base integer type of this enum.
`BASE_SIZE`
: An integer which will get the size (in bytes) of the base integer
type of this enum.
`NUM_MEMBERS`
: An integer which will get the number of members defined for this
enumeration type.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad type id.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
In this example from nf\_test/ftst\_vars3.F, an enum type is created and
then examined:
retval = nf_inq_enum(ncid, typeids(1), type_name, base_type,
& base_size, num_members)
if (retval .ne. nf_noerr) call handle_err(retval)
if (base_type .ne. NF_INT .or. num_members .ne. 2) stop 2
### 5.9.4 Learn the Name of a Enum Type: nf\_inq\_enum\_member
Get information about a member of an enum type.
Usage
-----
INTEGER FUNCTION NF_INQ_ENUM_MEMBER(INTEGER NCID, INTEGER XTYPE,
INTEGER IDX, CHARACTER*(*) NAME, INTEGER VALUE)
`NCID`
: The groupid where this enum type exists.
`XTYPE`
: The typeid for this enum type.
`IDX`
: The one-based index number for the member of interest.
`NAME`
: A character array which will get the name of the member. It will
have a maximum length of NF\_MAX\_NAME.
`VALUE`
: An integer that will get the value associated with this member.
Errors
------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad type id.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
Example
-------
This example is from nf\_test/ftst\_vars3.F:
C Check the members of the enum type.
retval = nf_inq_enum_member(ncid, typeids(1), 1, member_name,
& member_value)
if (retval .ne. nf_noerr) call handle_err(retval)
if (member_name(1:len(zero_name)) .ne. zero_name .or.
& member_value .ne. 0) stop 2
retval = nf_inq_enum_member(ncid, typeids(1), 2, member_name,
& member_value)
if (retval .ne. nf_noerr) call handle_err(retval)
if (member_name(1:len(one_name)) .ne. one_name .or.
& member_value .ne. 1) stop 2
### 5.9.5 Learn the Name of a Enum Type: NF\_INQ\_ENUM\_IDENT
Get the name which is associated with an enum member value.
This is similar to NF\_INQ\_ENUM\_MEMBER, but instead of using the index
of the member, you use the value of the member.
Usage
-----
INTEGER FUNCTION NF_INQ_ENUM_IDENT(INTEGER NCID, INTEGER XTYPE,
INTEGER VALUE, CHARACTER*(*) IDENTIFIER)
`NCID`
: The groupid where this enum type exists.
`XTYPE`
: The typeid for this enum type.
`VALUE`
: The value for which an identifier is sought.
`IDENTIFIER`
: A character array that will get the identifier. It will have a
maximum length of NF\_MAX\_NAME.
Return Code
-----------
`NF_NOERR`
: No error.
`NF_EBADTYPEID`
: Bad type id, or not an enum type.
`NF_EHDFERR`
: An error was reported by the HDF5 layer.
`NF_EINVAL`
: The value was not found in the enum.
Example
-------
In this example from nf\_test/ftst\_vars3.F, the values for 0 and 1 are
checked in an enum.
retval = nf_inq_enum_ident(ncid, typeids(1), 0, member_name)
if (retval .ne. nf_noerr) call handle_err(retval)
if (member_name(1:len(zero_name)) .ne. zero_name) stop 2
retval = nf_inq_enum_ident(ncid, typeids(1), 1, member_name)
if (retval .ne. nf_noerr) call handle_err(retval)
if (member_name(1:len(one_name)) .ne. one_name) stop 2
6. Variables
============
6.1 Variables Introduction
--------------------------
Variables for a netCDF dataset are defined when the dataset is created,
while the netCDF dataset is in define mode. Other variables may be added
later by reentering define mode. A netCDF variable has a name, a type,
and a shape, which are specified when it is defined. A variable may also
have values, which are established later in data mode.
Ordinarily, the name, type, and shape are fixed when the variable is
first defined. The name may be changed, but the type and shape of a
variable cannot be changed. However, a variable defined in terms of the
unlimited dimension can grow without bound in that dimension.
A netCDF variable in an open netCDF dataset is referred to by a small
integer called a variable ID.
Variable IDs reflect the order in which variables were defined within a
netCDF dataset. Variable IDs are 1, 2, 3,..., in the order in which the
variables were defined. A function is available for getting the variable
ID from the variable name and vice-versa.
Attributes (see [Attributes](#Attributes)) may be associated with a
variable to specifych properties as units.
Operationspported on variables are:
- Create a variable, given its name, data type, and shape.
- Get a variable ID from its name.
- Get a variable’s name, data type, shape, and number of attributes
from its ID.
- Put a data value into a variable, given variable ID, indices, and
value.
- Put an array of values into a variable, given variable ID, corner
indices, edge lengths, and a block of values.
- Put absampled or mapped array of values into a variable,
given variable ID, corner indices, edge lengths, stride vector,
index mapping vector, and a block of values.
- Get a data value from a variable, given variable ID and indices.
- Get an array of values from a variable, given variable ID, corner
indices, and edge lengths.
- Get absampled or mapped array of values from a variable,
given variable ID, corner indices, edge lengths, stride vector, and
index mapping vector.
- Rename a variable.
6.2 Language Types Corresponding to netCDF external data types
--------------------------------------------------------------
The following table gives the netCDF external data types and the
corresponding type constants for defining variables in the FORTRAN
interface:
-------- ---------------------- ------
Type FORTRAN API Mnemonic Bits
byte NF\_BYTE 8
char NF\_CHAR 8
short NF\_SHORT 16
int NF\_INT 32
float NF\_FLOAT 32
double NF\_DOUBLE 64
-------- ---------------------- ------
The first column gives the netCDF external data type, which is the same
as the CDL data type. The next column gives the corresponding FORTRAN
parameter for use in netCDF functions (the parameters are defined in the
netCDF FORTRAN include-file netcdf.inc). The last column gives the
number of bits used in the external representation of values of the
corresponding type.
Note that there are no netCDF types corresponding to 64-bit integers or
to characters wider than 8 bits in the current version of the netCDF
library.
6.3 Create a Variable: `NF_DEF_VAR`
-----------------------------------
The function NF\_DEF\_VAR adds a new variable to an open netCDF dataset
in define mode. It returns (as an argument) a variable ID, given the
netCDF ID, the variable name, the variable type, the number of
dimensions, and a list of the dimension IDs.
Usage
-----
INTEGER FUNCTION NF_DEF_VAR(INTEGER NCID, CHARACTER*(*) NAME,
INTEGER XTYPE, INTEGER NVDIMS,
INTEGER VDIMS(*), INTEGER varid)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`NAME`
: Variable name.
`XTYPE`
: One of the set of predefined netCDF external data types. The type of
this parameter, NF\_TYPE, is defined in the netCDF header file. The
valid netCDF external data types are NF\_BYTE, NF\_CHAR, NF\_SHORT,
NF\_INT, NF\_FLOAT, and NF\_DOUBLE. If the file is a NetCDF-4/HDF5
file, the additional types NF\_UBYTE, NF\_USHORT, NF\_UINT,
NF\_INT64, NF\_UINT64, and NF\_STRING may be used, as well as a user
defined type ID.
`NVDIMS`
: Number of dimensions for the variable. For example, 2 specifies a
matrix, 1 specifies a vector, and 0 means the variable is a scalar
with no dimensions. Must not be negative or greater than the
predefined constant NF\_MAX\_VAR\_DIMS.
`VDIMS`
: Vector of ndims dimension IDs corresponding to the variable
dimensions. If the ID of the unlimited dimension is included, it
must be first. This argument is ignored if ndims is 0. For expanded
model netCDF4/HDF5 files, there may be any number of unlimited
dimensions, and they may be used in any element of the dimids array.
`varid`
: Returned variable ID.
Errors
------
NF\_DEF\_VAR returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The netCDF dataset is not in define mode.
- The specified variable name is the name of another existing
variable.
- The specified type is not a valid netCDF type.
- The specified number of dimensions is negative or more than the
constant NF\_MAX\_VAR\_DIMS, the maximum number of dimensions
permitted for a netCDF variable.
- One or more of the dimension IDs in the list of dimensions is not a
valid dimension ID for the netCDF dataset.
- The number of variables would exceed the constant NF\_MAX\_VARS, the
maximum number of variables permitted in a netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_DEF\_VAR to create a variable named rh of
type double with three dimensions, time, lat, and lon in a new netCDF
dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
INTEGER LATDIM, LONDIM, TIMDIM ! dimension IDs
INTEGER RHID ! variable ID
INTEGER RHDIMS(3) ! variable shape
...
STATUS = NF_CREATE ('foo.nc', NF_NOCLOBBER, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! define dimensions
STATUS = NF_DEF_DIM(NCID, 'lat', 5, LATDIM)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_DEF_DIM(NCID, 'lon', 10, LONDIM)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_DEF_DIM(NCID, 'time', NF_UNLIMITED, TIMDIM)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! define variable
RHDIMS(1) = LONDIM
RHDIMS(2) = LATDIM
RHDIMS(3) = TIMDIM
STATUS = NF_DEF_VAR (NCID, 'rh', NF_DOUBLE, 3, RHDIMS, RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.4 Define Chunking Parameters for a Variable: `NF_DEF_VAR_CHUNKING`
--------------------------------------------------------------------
The function NF\_DEF\_VAR\_CHUNKING sets the storage parameters for a
variable in a netCDF-4 file. It can set the chunk sizes to get chunked
storage, or it can set the contiguous flag to get contiguous storage.
Variables that make use of one or more unlimited dimensions,
compression, or checms must use chunking. Such variables are created
with default chunk sizes of 1 for each unlimited dimension and the
dimension length for other dimensions, except that if the rlting
chunks are too large, the default chunk sizes for non-record dimensions
are reduced.
The total size of a chunk must be less than 4 GiB. That is, the product
of all chunksizes and the size of the data (or the size of nc\_vlen\_t
for VLEN types) must be less than 4 GiB.
This function may only be called after the variable is defined, but
before nc\_enddef is called. Once the chunking parameters are set for a
variable, they cannot be changed. This function can be used to change
the default chunking for record, compressed, or checmmed variables
before nc\_enddef is called.
Note that you cannot set chunking for scalar variables. Only non-scalar
variables can have chunking.
Usage
-----
NF_DEF_VAR_CHUNKING(INTEGER NCID, INTEGER VARID, INTEGER STORAGE, INTEGER CHUNKSIZES)
`ncid`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`varid`
: Variable ID.
`storage`
: If NF\_CONTIGUOUS, then contiguous storage is used for this
variable. Variables with compression, shuffle filter, checms, or
one or more unlimited dimensions cannot use contiguous storage. If
contiguous storage is turned on, the chunksizes parameter is
ignored.
If NF\_CHUNKED, then chunked storage is used for this variable.
Chunk sizes may be specified with the chunksizes parameter. Default
sizes will be used if chunking is required and this function is not
called.
By default contiguous storage is used for fix-sized variables when
conpression, chunking, checms, or endianness control are not
used.
`chunksizes`
: An array of chunk sizes. The array must have the one chunksize for
each dimension in the variable. If contiguous storage is used, then
the chunksizes parameter is ignored.
Errors
------
NF\_DEF\_VAR\_CHUNKING returns the value NF\_NOERR if no errors
occurred. Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_EINVAL`
: Invalid input. This can occur when the user attempts to set
contiguous storage for a variable with compression or checms, or
one or more unlimited dimensions.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
`NF_ELATEDEF`
: This variable has already been thebject of a NF\_ENDDEF call. In
netCDF-4 files NF\_ENDDEF will be called automatically for any data
read or write. Once enddef has been called, it is impossible to set
the chunking for a variable.
`NF_ENOTINDEFINE`
: Not in define mode. This is returned for netCDF classic or 64-bit
offset files, or for netCDF-4 files, when they were been created
with NF\_STRICT\_NC3 flag. (see
[NF\_CREATE](#NF_005fCREATE)).
`NF_ESTRICTNC3`
: Trying to create a var some place other than the root group in a
netCDF file with NF\_STRICT\_NC3 turned on.
Example
-------
In this example from nf\_test/ftst\_vars.F, a file is created, two
dimensions and a variable are defined, and the chunksizes of the data
are set to the size of the data (that is, data will be written in one
chunk).
C Create the netCDF file.
retval = nf_create(FILE_NAME, NF_NETCDF4, ncid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the dimensions.
retval = nf_def_dim(ncid, "x", NX, x_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_def_dim(ncid, "y", NY, y_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the variable.
dimids(1) = y_dimid
dimids(2) = x_dimid
retval = NF_DEF_VAR(ncid, "data", NF_INT, NDIMS, dimids, varid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Turn on chunking.
chunks(1) = NY
chunks(2) = NX
retval = NF_DEF_VAR_chunking(ncid, varid, NF_CHUNKED, chunks)
if (retval .ne. nf_noerr) call handle_err(retval)
6.5 Learn About Chunking Parameters for a Variable: `NF_INQ_VAR_CHUNKING`
-------------------------------------------------------------------------
The function NF\_INQ\_VAR\_CHUNKING returns the chunking settings for a
variable in a netCDF-4 file.
Usage
-----
NF_INQ_VAR_CHUNKING(INTEGER NCID, INTEGER VARID, INTEGER STORAGE, INTEGER CHUNKSIZES);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`STORAGE`
: On return, set to NF\_CONTIGUOUS if this variable uses contiguous
storage, NF\_CHUNKED if it uses chunked storage.
`CHUNKSIZES`
: An array of chunk sizes. The length of CHUNKSIZES must be the same
as the number of dimensions of the variable.
Errors
------
NF\_INQ\_VAR\_CHUNKING returns the value NF\_NOERR if no errors
occurred. Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
Example
-------
In this example from nf\_test/ftst\_vars.F, a variable with chunked
storage is checked to ere that the chunksizes are set to expected
values.
C Is everything set that ispposed to be?
retval = nf_inq_var_chunking(ncid, varid, storage, chunks_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (storage .ne. NF_CHUNKED) stop 2
if (chunks(1) .ne. chunks_in(1)) stop 2
if (chunks(2) .ne. chunks_in(2)) stop 2
6.6 Set HDF5 Chunk Cache for a Variable: NF\_SET\_VAR\_CHUNK\_CACHE
-------------------------------------------------------------------
This function changes the chunk cache settings for a variable. The
change in cache size happens immediately. This is a property of the open
file - it does not persist the next time you open the file.
For more information, see the documentation for the H5Pset\_cache()
function in the HDF5 library at the HDF5 website:
[http://hdfgroup.org/HDF5/](http://hdfgroup.org/HDF5/).
Usage
-----
NF_SET_VAR_CHUNK_CACHE(INTEGER NCID, INTEGER VARID, INTEGER SIZE, INTEGER NELEMS,
INTEGER PREEMPTION);
`NCID`
: NetCDF ID, from a previous call to nc\_open or nc\_create.
`VARID`
: Variable ID.
`SIZE`
: The total size of the raw data chunk cache, in megabytes. This
should be big enough to hold multiple chunks of data. (Note that the
C API uses bytes, but the Fortran APIs uses megabytes to avoid
numbers that can’t fit in 4-byte integers.)
`NELEMS`
: The number of chunk slots in the raw data chunk cache hash table.
This should be a prime number larger than the number of chunks that
will be in the cache.
`PREEMPTION`
: The preemption value must be between 0 and 100 inclusive and
indicates the degreee to which chunks that have been fully read are
favored for kicking out of the chunk cache, when needed. A value of
zero means fully read chunks are treated no differently than other
chunks (the preemption is strictly Least Recently Used) while a
value of 100 means fully read chunks are always preempted before
other chunks. (The C API uses a float between 0 and 1 for this
value).
Return Codes
------------
`NF_NOERR`
: No error.
`NF_EINVAL`
: Preemption must be between zero and 100 (inclusive).
Example
-------
This example is from nf\_test/ftst\_vars2.F:
include 'netcdf.inc'
...
C These will be used to set the per-variable chunk cache.
integer CACHE_SIZE, CACHE_NELEMS, CACHE_PREEMPTION
parameter (CACHE_SIZE = 8, CACHE_NELEMS = 571)
parameter (CACHE_PREEMPTION = 42)
...
C Set variable caches.
retval = nf_set_var_chunk_cache(ncid, varid(i), CACHE_SIZE,
& CACHE_NELEMS, CACHE_PREEMPTION)
if (retval .ne. nf_noerr) call handle_err(retval)
6.7 Get the HDF5 Chunk Cache Settings for a variable: NF\_GET\_VAR\_CHUNK\_CACHE
--------------------------------------------------------------------------------
This function gets the current chunk cache settings for a variable in a
netCDF-4/HDF5 file.
For more information, see the documentation for the H5Pget\_cache()
function in the HDF5 library at the HDF5 website:
[http://hdfgroup.org/HDF5/](http://hdfgroup.org/HDF5/).
Usage
-----
INTEGER NF_GET_VAR_CHUNK_CACHE(INTEGER NCID, INTEGER VARID, INTEGER SIZE, INTEGER NELEMS,
INTEGER PREEMPTION);
`ncid`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`varid`
: Variable ID.
`sizep`
: The total size of the raw data chunk cache, in megabytes, will be
put here.
`nelemsp`
: The number of chunk slots in the raw data chunk cache hash table
will be put here.
`preemptionp`
: The preemption will be put here. The preemtion value is between 0
and 100 inclusive and indicates how much chunks that have been fully
read are favored for preemption. A value of zero means fully read
chunks are treated no differently than other chunks (the preemption
is strictly LRU) while a value of 100 means fully read chunks are
always preempted before other chunks.
Return Codes
------------
`NC_NOERR`
: No error.
Example
-------
This example is from nf\_test/ftst\_vars2.c:
include 'netcdf.inc'
...
C These will be used to set the per-variable chunk cache.
integer CACHE_SIZE, CACHE_NELEMS, CACHE_PREEMPTION
parameter (CACHE_SIZE = 8, CACHE_NELEMS = 571)
parameter (CACHE_PREEMPTION = 42)
C These will be used to check the setting of the per-variable chunk
C cache.
integer cache_size_in, cache_nelems_in, cache_preemption_in
...
retval = nf_get_var_chunk_cache(ncid, varid(i), cache_size_in,
& cache_nelems_in, cache_preemption_in)
if (retval .ne. nf_noerr) call handle_err(retval)
if (cache_size_in .ne. CACHE_SIZE .or. cache_nelems_in .ne.
& CACHE_NELEMS .or. cache_preemption .ne. CACHE_PREEMPTION)
& stop 8
6.8 Define Fill Parameters for a Variable: `nf_def_var_fill`
------------------------------------------------------------
The function NF\_DEF\_VAR\_FILL sets the fill parameters for a variable
in a netCDF-4 file.
This function must be called after the variable is defined, but before
NF\_ENDDEF is called.
Usage
-----
NF_DEF_VAR_FILL(INTEGER NCID, INTEGER VARID, INTEGER NO_FILL, FILL_VALUE);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`NO_FILL`
: Set to non-zero value to set no\_fill mode on a variable. When this
mode is on, fill values will not be written for the variable. This
is helpful in high performance applications. For netCDF-4/HDF5 files
(whether classic model or not), this may only be changed after the
variable is defined, but before it is committed to disk (i.e. before
the first NF\_ENDDEF after the NF\_DEF\_VAR.) For classic and 64-bit
offset file, the no\_fill mode may be turned on and off at any time.
`FILL_VALUE`
: A value which will be used as the fill value for the variable. Must
be the same type as the variable. This will be written to a
\_FillValue attribute, created for this purpose. If NULL, this
argument will be ignored.
Return Codes
------------
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
`NF_ELATEDEF`
: This variable has already been thebject of a NF\_ENDDEF call. In
netCDF-4 files NF\_ENDDEF will be called automatically for any data
read or write. Once enddef has been called, it is impossible to set
the fill for a variable.
`NF_ENOTINDEFINE`
: Not in define mode. This is returned for netCDF classic or 64-bit
offset files, or for netCDF-4 files, when they were been created
with NF\_STRICT\_NC3 flag. (see
[NF\_CREATE](#NF_005fCREATE)).
`NF_EPERM`
: Attempt to create object in read-only file.
Example
-------
6.9 Learn About Fill Parameters for a Variable: `NF_INQ_VAR_FILL`
-----------------------------------------------------------------
The function NF\_INQ\_VAR\_FILL returns the fill settings for a variable
in a netCDF-4 file.
Usage
-----
NF_INQ_VAR_FILL(INTEGER NCID, INTEGER VARID, INTEGER NO_FILL, FILL_VALUE)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`NO_FILL`
: An integer which will get a 1 if no\_fill mode is set for this
variable, and a zero if it is not set
`FILL_VALUE`
: This will get the fill value for this variable. This parameter will
be ignored if it is NULL.
Return Codes
------------
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
Example
-------
6.10 Define Compression Parameters for a Variable: `NF_DEF_VAR_DEFLATE`
-----------------------------------------------------------------------
The function NF\_DEF\_VAR\_DEFLATE sets the deflate parameters for a
variable in a netCDF-4 file.
When using parallel I/O for writing data, deflate cannot be used. This
is because the compression makes it impossible for the HDF5 library to
exactly map the data to disk location.
(Deflated data can be read with parallel I/O).
NF\_DEF\_VAR\_DEFLATE must be called after the variable is defined, but
before NF\_ENDDEF is called.
Usage
-----
NF_DEF_VAR_DEFLATE(INTEGER NCID, INTEGER VARID, INTEGER SHUFFLE, INTEGER DEFLATE,
INTEGER DEFLATE_LEVEL);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`SHUFFLE`
: If non-zero, turn on the shuffle filter.
`DEFLATE`
: If non-zero, turn on the deflate filter at the level specified by
the deflate\_level parameter.
`DEFLATE_LEVEL`
: Must be between 0 (no deflate, the default) and 9 (slowest, but
“best” deflate).
If set to zero, no deflation takes place and the def\_var\_deflate
call is ignored. This is slightly different from HDF5 handing of 0
deflate, which turns on the filter but makes only trivial changes to
the data.
Informal testing at NetCDF World Headquartersggests that there is
little to be gained (with the limited set of test data used here),
in setting the deflate level above 2 or 3.
Errors
------
NF\_DEF\_VAR\_DEFLATE returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
`NF_ELATEDEF`
: This variable has already been thebject of a NF\_ENDDEF call. In
netCDF-4 files NF\_ENDDEF will be called automatically for any data
read or write. Once enddef has been called, it is impossible to set
the deflate for a variable.
`NF_ENOTINDEFINE`
: Not in define mode. This is returned for netCDF classic or 64-bit
offset files, or for netCDF-4 files, when they were been created
with NF\_STRICT\_NC3 flag. (see
[NF\_CREATE](#NF_005fCREATE)).
`NF_EPERM`
: Attempt to create object in read-only file.
`NF_EINVAL`
: Invalid deflate\_level. The deflate level must be between 0 and 9,
inclusive.
Example
-------
In this example from nf\_test/ftst\_vars.F, a file is created with two
dimensions and one variable. Chunking, deflate, and the fletcher32
filter are turned on. The deflate level is set to 4 below.
C Create the netCDF file.
retval = nf_create(FILE_NAME, NF_NETCDF4, ncid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the dimensions.
retval = nf_def_dim(ncid, "x", NX, x_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_def_dim(ncid, "y", NY, y_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the variable.
dimids(1) = y_dimid
dimids(2) = x_dimid
retval = NF_DEF_VAR(ncid, "data", NF_INT, NDIMS, dimids, varid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Turn on chunking.
chunks(1) = NY
chunks(2) = NX
retval = NF_DEF_VAR_CHUNKING(ncid, varid, NF_CHUNKED, chunks)
if (retval .ne. nf_noerr) call handle_err(retval)
C Turn on deflate compression, fletcher32 checm.
retval = NF_DEF_VAR_deflate(ncid, varid, 0, 1, 4)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = NF_DEF_VAR_FLETCHER32(ncid, varid, NF_FLETCHER32)
if (retval .ne. nf_noerr) call handle_err(retval)
6.11 Learn About Deflate Parameters for a Variable: `NF_INQ_VAR_DEFLATE`
------------------------------------------------------------------------
The function NF\_INQ\_VAR\_DEFLATE returns the deflate settings for a
variable in a netCDF-4 file.
It is not necessary to know the deflate settings to read the variable.
(Deflate is completely transparent to readers of the data).
Usage
-----
NF_INQ_VAR_DEFLATE(INTEGER NCID, INTEGER VARID, INTEGER SHUFFLE,
INTEGER DEFLATE, INTEGER DEFLATE_LEVEL);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`SHUFFLE`
: NF\_INQ\_VAR\_DEFLATE will set this to a 1 if the shuffle filter is
turned on for this variable, and a 0 otherwise.
`DEFLATE`
: NF\_INQ\_VAR\_DEFLATE will set this to a 1 if the deflate filter is
turned on for this variable, and a 0 otherwise.
`DEFLATE_LEVEL`
: NF\_INQ\_VAR\_DEFLATE function will write the deflate\_level here,
if deflate is in use.
Errors
------
NF\_INQ\_VAR\_DEFLATE returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
Example
-------
In this example code from nf\_test/ftst\_vars.F, a file with a variable
using deflate is opened, and the deflate level checked.
C Is everything set that ispposed to be?
retval = nf_inq_var_deflate(ncid, varid, shuffle, deflate,
+ deflate_level)
if (retval .ne. nf_noerr) call handle_err(retval)
if (shuffle .ne. 0 .or. deflate .ne. 1 .or.
+ deflate_level .ne. 4) stop 2
6.12 Learn About Szip Parameters for a Variable: `NF_INQ_VAR_SZIP`
------------------------------------------------------------------
The function NF\_INQ\_VAR\_SZIP returns the szip settings for a variable
in a netCDF-4 file.
It is not necessary to know the szip settings to read the variable.
(Szip is completely transparent to readers of the data).
Usage
-----
NF_INQ_VAR_SZIP(INTEGER NCID, INTEGER VARID, INTEGER OPTION_MASK,
PIXELS_PER_BLOCK);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`OPTION_MASK`
: This will be set to the option\_mask value.
`PIXELS_PER_BLOCK`
: The number of bits per pixel will be put here.
Errors
------
NF\_INQ\_VAR\_SZIP returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
6.13 Define Checm Parameters for a Variable: `NF_DEF_VAR_FLETCHER32`
-----------------------------------------------------------------------
The function NF\_DEF\_VAR\_FLETCHER32 sets the checm property for a
variable in a netCDF-4 file.
This function may only be called after the variable is defined, but
before NF\_ENDDEF is called.
Usage
-----
NF_DEF_VAR_FLETCHER32(INTEGER NCID, INTEGER VARID, INTEGER CHECKSUM);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`CHECKSUM`
: If this is NF\_FLETCHER32, fletcher32 checms will be turned on
for this variable.
Errors
------
NF\_DEF\_VAR\_FLETCHER32 returns the value NF\_NOERR if no errors
occurred. Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
`NF_ELATEDEF`
: This variable has already been thebject of a NF\_ENDDEF call. In
netCDF-4 files NF\_ENDDEF will be called automatically for any data
read or write. Once enddef has been called, it is impossible to set
the checm property for a variable.
`NF_ENOTINDEFINE`
: Not in define mode. This is returned for netCDF classic or 64-bit
offset files, or for netCDF-4 files, when they were been created
with NF\_STRICT\_NC3 flag. (see
[NF\_CREATE](#NF_005fCREATE)).
`NF_EPERM`
: Attempt to create object in read-only file.
Example
-------
In this example from nf\_test/ftst\_vars.F, the variable in a file has
the Fletcher32 checm filter turned on.
C Create the netCDF file.
retval = nf_create(FILE_NAME, NF_NETCDF4, ncid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the dimensions.
retval = nf_def_dim(ncid, "x", NX, x_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_def_dim(ncid, "y", NY, y_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the variable.
dimids(1) = y_dimid
dimids(2) = x_dimid
retval = NF_DEF_VAR(ncid, "data", NF_INT, NDIMS, dimids, varid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Turn on chunking.
chunks(1) = NY
chunks(2) = NX
retval = NF_DEF_VAR_CHUNKING(ncid, varid, NF_CHUNKED, chunks)
if (retval .ne. nf_noerr) call handle_err(retval)
C Turn on deflate compression, fletcher32 checms.
retval = NF_DEF_VAR_DEFLATE(ncid, varid, 0, 1, 4)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = NF_DEF_VAR_FLETCHER32(ncid, varid, NF_FLETCHER32)
if (retval .ne. nf_noerr) call handle_err(retval)
6.14 Learn About Checm Parameters for a Variable: `NF_INQ_VAR_FLETCHER32`
----------------------------------------------------------------------------
The function NF\_INQ\_VAR\_FLETCHER32 returns the checm settings for
a variable in a netCDF-4 file.
Usage
-----
NF_INQ_VAR_FLETCHER32(INTEGER NCID, INTEGER VARID, INTEGER CHECKSUM);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`CHECKSUM`
: NF\_INQ\_VAR\_FLETCHER32 will set this to NF\_FLETCHER32 if the
fletcher32 filter is turned on for this variable, and NF\_NOCHECKSUM
if it is not.
Errors
------
NF\_INQ\_VAR\_FLETCHER32 returns the value NF\_NOERR if no errors
occurred. Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
Example
-------
In this example from nf\_test/ftst\_vars.F the checm filter is
checked for a file. Since it was turned on for this variable, the
checm variable is set to NF\_FLETCHER32.
retval = nf_inq_var_fletcher32(ncid, varid, checm)
if (retval .ne. nf_noerr) call handle_err(retval)
if (checm .ne. NF_FLETCHER32) stop 2
6.15 Define Endianness of a Variable: `NF_DEF_VAR_ENDIAN`
---------------------------------------------------------
The function NF\_DEF\_VAR\_ENDIAN sets the endianness for a variable in
a netCDF-4 file.
This function must be called after the variable is defined, but before
NF\_ENDDEF is called.
By default, netCDF-4 variables are in native endianness. That is, they
are big-endian on a big-endian machine, and little-endian on a little
endian machine.
In some cases a user might wish to change from native endianness to
either big or little-endianness. This function allows them to do that.
Usage
-----
NF_DEF_VAR_ENDIAN(INTEGER NCID, INTEGER VARID, INTEGER ENDIAN)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`ENDIAN`
: Set to NF\_ENDIAN\_NATIVE for native endianness. (This is the
default). Set to NF\_ENDIAN\_LITTLE for little endian, or
NF\_ENDIAN\_BIG for big endian.
Errors
------
NF\_DEF\_VAR\_ENDIAN returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
`NF_ELATEDEF`
: This variable has already been thebject of a NF\_ENDDEF call. In
netCDF-4 files NF\_ENDDEF will be called automatically for any data
read or write. Once enddef has been called, it is impossible to set
the endianness of a variable.
`NF_ENOTINDEFINE`
: Not in define mode. This is returned for netCDF classic or 64-bit
offset files, or for netCDF-4 files, when they were been created
with NF\_STRICT\_NC3 flag, and the file is not in define mode. (see
[NF\_CREATE](#NF_005fCREATE)).
`NF_EPERM`
: Attempt to create object in read-only file.
Example
-------
In this example from nf\_test/ftst\_vars.c, a file is created with one
variable, and its endianness is set to NF\_ENDIAN\_BIG.
C Create the netCDF file.
retval = nf_create(FILE_NAME, NF_NETCDF4, ncid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the dimensions.
retval = nf_def_dim(ncid, "x", NX, x_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
retval = nf_def_dim(ncid, "y", NY, y_dimid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Define the variable.
dimids(1) = y_dimid
dimids(2) = x_dimid
retval = NF_DEF_VAR(ncid, "data", NF_INT, NDIMS, dimids, varid)
if (retval .ne. nf_noerr) call handle_err(retval)
C Turn on chunking.
chunks(1) = NY
chunks(2) = NX
retval = NF_DEF_VAR_chunking(ncid, varid, 0, chunks)
if (retval .ne. nf_noerr) call handle_err(retval)
C Set variable to big-endian (default is whatever is native to
C writing machine).
retval = NF_DEF_VAR_endian(ncid, varid, NF_ENDIAN_BIG)
if (retval .ne. nf_noerr) call handle_err(retval)
6.16 Learn About Endian Parameters for a Variable: `NF_INQ_VAR_ENDIAN`
----------------------------------------------------------------------
The function NF\_INQ\_VAR\_ENDIAN returns the endianness settings for a
variable in a netCDF-4 file.
Usage
-----
NF_INQ_VAR_ENDIAN(INTEGER NCID, INTEGER VARID, INTEGER ENDIAN)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`ENDIAN`
: NF\_INQ\_VAR\_ENDIAN will set this to NF\_ENDIAN\_LITTLE if this
variable is stored in little-endian format, NF\_ENDIAN\_BIG if it is
stored in big-endian format, and NF\_ENDIAN\_NATIVE if the
endianness is not set, and the variable is not created yet.
Errors
------
NF\_INQ\_VAR\_ENDIAN returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error.
Possible return codes include:
`NF_NOERR`
: No error.
`NF_BADID`
: Bad ncid.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_ENOTVAR`
: Can’t find this variable.
Example
-------
In this example from nf\_test/ftst\_vars.F, the endianness of a variable
is checked to makere it is NF\_ENDIAN\_BIG.
retval = nf_inq_var_endian(ncid, varid, endianness)
if (retval .ne. nf_noerr) call handle_err(retval)
if (endianness .ne. NF_ENDIAN_BIG) stop 2
6.17 Get a Variable ID from Its Name: NF\_INQ\_VARID
----------------------------------------------------
The function NF\_INQ\_VARID returns the ID of a netCDF variable, given
its name.
Usage
-----
INTEGER FUNCTION NF_INQ_VARID(INTEGER NCID, CHARACTER*(*) NAME,
INTEGER varid)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`NAME`
: Variable name for which ID is desired.
`varid`
: Returned variable ID.
Errors
------
NF\_INQ\_VARID returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The specified variable name is not a valid name for a variable in
the specified netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_INQ\_VARID to find out the ID of a variable
named rh in an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID, RHID
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.18 Get Information about a Variable from Its ID: NF\_INQ\_VAR family
----------------------------------------------------------------------
A family of functions that returns information about a netCDF variable,
given its ID. Information about a variable includes its name, type,
number of dimensions, a list of dimension IDs describing the shape of
the variable, and the number of variable attributes that have been
assigned to the variable.
The function NF\_INQ\_VAR returns all the information about a netCDF
variable, given its ID. The other functions each return just one item of
information about a variable.
These other functions include NF\_INQ\_VARNAME, NF\_INQ\_VARTYPE,
NF\_INQ\_VARNDIMS, NF\_INQ\_VARDIMID, and NF\_INQ\_VARNATTS.
Usage
-----
INTEGER FUNCTION NF_INQ_VAR (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) name, INTEGER xtype,
INTEGER ndims, INTEGER dimids(*),
INTEGER natts)
INTEGER FUNCTION NF_INQ_VARNAME (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) name)
INTEGER FUNCTION NF_INQ_VARTYPE (INTEGER NCID, INTEGER VARID,
INTEGER xtype)
INTEGER FUNCTION NF_INQ_VARNDIMS (INTEGER NCID, INTEGER VARID,
INTEGER ndims)
INTEGER FUNCTION NF_INQ_VARDIMID (INTEGER NCID, INTEGER VARID,
INTEGER dimids(*))
INTEGER FUNCTION NF_INQ_VARNATTS (INTEGER NCID, INTEGER VARID,
INTEGER natts)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`NAME`
: Returned variable name. The caller must allocate space for the
returned name. The maximum possible length, in characters, of a
variable name is given by the predefined constant NF\_MAX\_NAME.
`xtype`
: Returned variable type, one of the set of predefined netCDF external
data types. The type of this parameter, NF\_TYPE, is defined in the
netCDF header file. The valid netCDF external data types are
NF\_BYTE, NF\_CHAR, NF\_SHORT, NF\_INT, NF\_FLOAT, AND NF\_DOUBLE.
`ndims`
: Returned number of dimensions the variable was defined as using. For
example, 2 indicates a matrix, 1 indicates a vector, and 0 means the
variable is a scalar with no dimensions.
`dimids`
: Returned vector of \*ndimsp dimension IDs corresponding to the
variable dimensions. The caller must allocate enough space for a
vector of at least \*ndimsp integers to be returned. The maximum
possible number of dimensions for a variable is given by the
predefined constant NF\_MAX\_VAR\_DIMS.
`natts`
: Returned number of variable attributes assigned to this variable.
These functions return the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_INQ\_VAR to find out about a variable named
rh in an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
CHARACTER*31 RHNAME ! variable name
INTEGER RHTYPE ! variable type
INTEGER RHN ! number of dimensions
INTEGER RHDIMS(NF_MAX_VAR_DIMS) ! variable shape
INTEGER RHNATT ! number of attributes
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID) ! get ID
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_VAR (NCID, RHID, RHNAME, RHTYPE, RHN, RHDIMS, RHNATT)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.19 Write a Single Data Value: NF\_PUT\_VAR1\_ type
----------------------------------------------------
The functions NF\_PUT\_VAR1\_type (for various types) put a single data
value of the specified type into a variable of an open netCDF dataset
that is in data mode. Inputs are the netCDF ID, the variable ID, an
index that specifies which value to add or alter, and the data value.
The value is converted to the external data type of the variable, if
necessary.
Usage
-----
INTEGER FUNCTION NF_PUT_VAR1_TEXT(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), CHARACTER CHVAL)
INTEGER FUNCTION NF_PUT_VAR1_INT1(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), INTEGER*1 I1VAL)
INTEGER FUNCTION NF_PUT_VAR1_INT2(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), INTEGER*2 I2VAL)
INTEGER FUNCTION NF_PUT_VAR1_INT (INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), INTEGER IVAL)
INTEGER FUNCTION NF_PUT_VAR1_REAL(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), REAL RVAL)
INTEGER FUNCTION NF_PUT_VAR1_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), DOUBLE DVAL)
INTEGER FUNCTION NF_PUT_VAR1(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), *)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`INDEX`
: The index of the data value to be written. The indices are relative
to 1, so for example, the first data value of a two-dimensional
variable would have index (1,1). The elements of index must
correspond to the variable’s dimensions. Hence, if the variable uses
the unlimited dimension, the last index would correspond to the
record number.
`CHVAL`\
`I1VAL`\
`I2VAL`\
`IVAL`\
`RVAL`\
`DVAL`
: Pointer to the data value to be written. If the type of data values
differs from the netCDF variable type, type conversion will occur.
See [(netcdf)Type Conversion](netcdf.html#Type-Conversion)
‘Type Conversion’ in The NetCDF Users Guide.
Errors
------
NF\_PUT\_VAR1\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified indices were out of range for the rank of the
specified variable. For example, a negative index or an index that
is larger than the corresponding dimension length will cause an
error.
- The specified value is out of the range of values representable by
the external data type of the variable.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_PUT\_VAR1\_DOUBLE to set the (4,3,2)
element of the variable named rh to 0.5 in an existing netCDF dataset
named foo.nc. For simplicity in this example, we ame that we know
that rh is dimensioned with lon, lat, and time, so we want to set the
value of rh that corresponds to the fourth lon value, the third lat
value, and the second time value:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS ! error status
INTEGER NCID
INTEGER RHID ! variable ID
INTEGER RHINDX(3) ! where to put value
DATA RHINDX /4, 3, 2/
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID) ! get ID
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_PUT_VAR1_DOUBLE (NCID, RHID, RHINDX, 0.5)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.20 Write an Entire Variable: NF\_PUT\_VAR\_ type
--------------------------------------------------
The NF\_PUT\_VAR\_ type family of functions write all the values of a
variable into a netCDF variable of an open netCDF dataset. This is the
simplest interface to use for writing a value in a scalar variable or
whenever all the values of a multidimensional variable can all be
written at once. The values to be written are associated with the netCDF
variable by aming that the last dimension of the netCDF variable
varies fastest in the C interface. The values are converted to the
external data type of the variable, if necessary.
Take care when using the simplest forms of this interface with record
variables (variables that use the NF\_UNLIMITED dimension) when you
don’t specify how many records are to be written. If you try to write
all the values of a record variable into a netCDF file that has no
record data yet (hence has 0 records), nothing will be written.
Similarly, if you try to write all the values of a record variable from
an array but there are more records in the file than you ame, more
in-memory data will be accessed than you expect, which may cause a
segmentation violation. To avoidch problems, it is better to use the
NF\_PUT\_VARA\_type interfaces for variables that use the NF\_UNLIMITED
dimension. See [Write an Array of Values: NF\_PUT\_VARA\_
type](#NF_005fPUT_005fVARA_005f-type).
Usage
-----
INTEGER FUNCTION NF_PUT_VAR_TEXT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) TEXT)
INTEGER FUNCTION NF_PUT_VAR_INT1 (INTEGER NCID, INTEGER VARID,
INTEGER*1 I1VALS(*))
INTEGER FUNCTION NF_PUT_VAR_INT2 (INTEGER NCID, INTEGER VARID,
INTEGER*2 I2VALS(*))
INTEGER FUNCTION NF_PUT_VAR_INT (INTEGER NCID, INTEGER VARID,
INTEGER IVALS(*))
INTEGER FUNCTION NF_PUT_VAR_REAL (INTEGER NCID, INTEGER VARID,
REAL RVALS(*))
INTEGER FUNCTION NF_PUT_VAR_DOUBLE(INTEGER NCID, INTEGER VARID,
DOUBLE DVALS(*))
INTEGER FUNCTION NF_PUT_VAR (INTEGER NCID, INTEGER VARID,
VALS(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`\
`VALS`
: The block of data values to be written. The data should be of the
type appropriate for the function called. You cannot put CHARACTER
data into a numeric variable or numeric data into a text variable.
For numeric data, if the type of data differs from the netCDF
variable type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide). The order in which the data will be
written into the specified variable is with the first dimension
varying fastest (like the ordinary FORTRAN convention).
Errors
------
Members of the NF\_PUT\_VAR\_ type family return the value NF\_NOERR if
no errors occurred. Otherwise, the returned status indicates an error.
Possible causes of errors include:
- The variable ID is invalid for the specified netCDF dataset.
- One or more of the specified values are out of the range of values
representable by the external data type of the variable.
- One or more of the specified values are out of the range of values
representable by the external data type of the variable.
- The specified netCDF dataset is in define mode rather than data
mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_PUT\_VAR\_DOUBLE to add or change all the
values of the variable named rh to 0.5 in an existing netCDF dataset
named foo.nc. For simplicity in this example, we ame that we know
that rh is dimensioned with lon and lat, and that there are ten lon
values and five lat values.
INCLUDE 'netcdf.inc'
...
PARAMETER (LATS=5, LONS=10) ! dimension lengths
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
DOUBLE RHVALS(LONS, LATS)
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
DO 10 ILON = 1, LONS
DO 10 ILAT = 1, LATS
RHVALS(ILON, ILAT) = 0.5
10 CONTINUE
STATUS = NF_PUT_var_DOUBLE (NCID, RHID, RHVALS)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.21 Write an Array of Values: NF\_PUT\_VARA\_ type
---------------------------------------------------
The function NF\_PUT\_VARA\_ type writes values into a netCDF variable
of an open netCDF dataset. The part of the netCDF variable to write is
specified by giving a corner and a vector of edge lengths that refer to
an array of the netCDF variable. The values to be written are
associated with the netCDF variable by aming that the first dimension
of the netCDF variable varies fastest in the FORTRAN interface. The
netCDF dataset must be in data mode.
Usage
-----
INTEGER FUNCTION NF_PUT_VARA_TEXT(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
CHARACTER*(*) TEXT)
INTEGER FUNCTION NF_PUT_VARA_INT1(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER*1 I1VALS(*))
INTEGER FUNCTION NF_PUT_VARA_INT2(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER*2 I2VALS(*))
INTEGER FUNCTION NF_PUT_VARA_INT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER IVALS(*))
INTEGER FUNCTION NF_PUT_VARA_REAL(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
REAL RVALS(*))
INTEGER FUNCTION NF_PUT_VARA_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
DOUBLE DVALS(*))
INTEGER FUNCTION NF_PUT_VARA (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
VALS(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`START`
: A vector of integers specifying the index in the variable where the
first of the data values will be written. The indices are relative
to 1, so for example, the first data value of a variable would have
index (1, 1, ..., 1). The length of START must be the same as the
number of dimensions of the specified variable. The elements of
START must correspond to the variable’s dimensions in order. Hence,
if the variable is a record variable, the last index would
correspond to the starting record number for writing the data
values.
`COUNT`
: A vector of integers specifying the edge lengths along each
dimension of the block of data values to written. To write a single
value, for example, specify COUNT as (1, 1, ..., 1). The length of
COUNT is the number of dimensions of the specified variable. The
elements of COUNT correspond to the variable’s dimensions. Hence, if
the variable is a record variable, the last element of COUNT
corresponds to a count of the number of records to write.
Note: setting any element of the count array to zero causes the
function to exit without error, and without doing anything.
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`\
`VALS`
: The block of data values to be written. The data should be of the
type appropriate for the function called. You cannot put CHARACTER
data into a numeric variable or numeric data into a text variable.
For numeric data, if the type of data differs from the netCDF
variable type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_PUT\_VARA\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified corner indices were out of range for the rank of the
specified variable. For example, a negative index, or an index that
is larger than the corresponding dimension length will cause an
error.
- The specified edge lengths added to the specified corner would have
referenced data out of range for the rank of the specified variable.
For example, an edge length that is larger than the corresponding
dimension length minus the corner index will cause an error.
- One or more of the specified values are out of the range of values
representable by the external data type of the variable.
- The specified netCDF dataset is in define mode rather than data
mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_PUT\_VARA\_DOUBLE to add or change all the
values of the variable named rh to 0.5 in an existing netCDF dataset
named foo.nc. For simplicity in this example, we ame that we know
that rh is dimensioned with time, lat, and lon, and that there are three
time values, five lat values, and ten lon values.
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIMS=3) ! number of dimensions
PARAMETER (TIMES=3, LATS=5, LONS=10) ! dimension lengths
INTEGER STATUS, NCID, TIMES
INTEGER RHID ! variable ID
INTEGER START(NDIMS), COUNT(NDIMS)
DOUBLE RHVALS(LONS, LATS, TIMES)
DATA START /1, 1, 1/ ! start at first value
DATA COUNT /LONS, LATS, TIMES/
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
DO 10 ILON = 1, LONS
DO 10 ILAT = 1, LATS
DO 10 ITIME = 1, TIMES
RHVALS(ILON, ILAT, ITIME) = 0.5
10 CONTINUE
STATUS = NF_PUT_VARA_DOUBLE (NCID, RHID, START, COUNT, RHVALS)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.22 NF\_PUT\_VARS\_ type
-------------------------
Each member of the family of functions NF\_PUT\_VARS\_ type writes a
subsampled (strided) array of values into a netCDF variable of
an open netCDF dataset. Thebsampled array is specified by
giving a corner, a vector of counts, and a stride vector. The netCDF
dataset must be in data mode.
Usage
-----
INTEGER FUNCTION NF_PUT_VARS_TEXT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*),CHARACTER*(*) TEXT)
INTEGER FUNCTION NF_PUT_VARS_INT1 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*),INTEGER*1 I1VALS(*))
INTEGER FUNCTION NF_PUT_VARS_INT2 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*),INTEGER*2 I2VALS(*))
INTEGER FUNCTION NF_PUT_VARS_INT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IVALS(*))
INTEGER FUNCTION NF_PUT_VARS_REAL (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), REAL RVALS(*))
INTEGER FUNCTION NF_PUT_VARS_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), DOUBLE DVALS(*))
INTEGER FUNCTION NF_PUT_VARS (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), VALS(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`START`
: A vector of integers specifying the index in the variable where the
first of the data values will be written. The indices are relative
to 1, so for example, the first data value of a variable would have
index (1, 1, ..., 1). The elements of START correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last index would correspond to the starting record
number for writing the data values.
`COUNT`
: A vector of integers specifying the number of indices selected along
each dimension. To write a single value, for example, specify COUNT
as (1, 1, ..., 1). The elements of COUNT correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last element of COUNT corresponds to a count of the
number of records to write.
Note: setting any element of the count array to zero causes the
function to exit without error, and without doing anything.
`STRIDE`
: A vector of integers that specifies the sampling interval along each
dimension of the netCDF variable. The elements of the stride vector
correspond, in order, to the netCDF variable’s dimensions (STRIDE(1)
gives the sampling interval along the most rapidly varying dimension
of the netCDF variable). Sampling intervals are specified in
type-independent units of elements (a value of 1 selects consecutive
elements of the netCDF variable along the corresponding dimension, a
value of 2 selects every other element, etc.).
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`\
`VALS`
: The block of data values to be written. The data should be of the
type appropriate for the function called. You cannot put CHARACTER
data into a numeric variable or numeric data into a text variable.
For numeric data, if the type of data differs from the netCDF
variable type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_PUT\_VARS\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified start, count and stride generate an index which is out
of range.
- One or more of the specified values are out of the range of values
representable by the external data type of the variable.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example of using NF\_PUT\_VARS\_REAL to write – from an
internal array – every other point of a netCDF variable named rh which
is described by the FORTRAN declaration REAL RH(6,4) (note the size of
the dimensions):
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIM=2) ! rank of netCDF variable
INTEGER NCID ! netCDF dataset ID
INTEGER STATUS ! return code
INTEGER RHID ! variable ID
INTEGER START(NDIM) ! netCDF variable start point
INTEGER COUNT(NDIM) ! size of internal array
INTEGER STRIDE(NDIM) ! netCDF variablebsampling intervals
REAL RH(3,2) ! notebsampled sizes for netCDF variable
! dimensions
DATA START /1, 1/ ! start at first netCDF variable value
DATA COUNT /3, 2/ ! size of internal array: entire bsampled)
! netCDF variable
DATA STRIDE /2, 2/ ! access every other netCDF element
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID(NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_PUT_VARS_REAL(NCID, RHID, START, COUNT, STRIDE, RH)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.23 NF\_PUT\_VARM\_ type
-------------------------
The NF\_PUT\_VARM\_ type family of functions writes a mapped array
section of values into a netCDF variable of an open netCDF dataset. The
mapped array is specified by giving a corner, a vector of
counts, a stride vector, and an index mapping vector. The index mapping
vector is a vector of integers that specifies the mapping between the
dimensions of a netCDF variable and the in-memory structure of the
internal data array. No amptions are made about the ordering or
length of the dimensions of the data array. The netCDF dataset must be
in data mode.
Usage
-----
INTEGER FUNCTION NF_PUT_VARM_TEXT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
CHARACTER*(*) TEXT)
INTEGER FUNCTION NF_PUT_VARM_INT1 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
INTEGER*1 I1VALS(*))
INTEGER FUNCTION NF_PUT_VARM_INT2 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
INTEGER*2 I2VALS(*))
INTEGER FUNCTION NF_PUT_VARM_INT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
INTEGER IVALS(*))
INTEGER FUNCTION NF_PUT_VARM_REAL (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
REAL RVALS(*))
INTEGER FUNCTION NF_PUT_VARM_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
DOUBLE DVALS(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`START`
: A vector of integers specifying the index in the variable where the
first of the data values will be written. The indices are relative
to 1, so for example, the first data value of a variable would have
index (1, 1, ..., 1). The elements of START correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last index would correspond to the starting record
number for writing the data values.
`COUNT`
: A vector of integers specifying the number of indices selected along
each dimension. To write a single value, for example, specify COUNT
as (1, 1, ..., 1). The elements of COUNT correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last element of COUNT corresponds to a count of the
number of records to write.
Note: setting any element of the count array to zero causes the
function to exit without error, and without doing anything.
`STRIDE`
: A vector of integers that specifies the sampling interval along each
dimension of the netCDF variable. The elements of the stride vector
correspond, in order, to the netCDF variable’s dimensions (STRIDE(1)
gives the sampling interval along the most rapidly varying dimension
of the netCDF variable). Sampling intervals are specified in
type-independent units of elements (a value of 1 selects consecutive
elements of the netCDF variable along the corresponding dimension, a
value of 2 selects every other element, etc.).
`IMAP`
: A vector of integers that specifies the mapping between the
dimensions of a netCDF variable and the in-memory structure of the
internal data array. The elements of the index mapping vector
correspond, in order, to the netCDF variable’s dimensions (IMAP(1)
gives the distance between elements of the internal array
corresponding to the most rapidly varying dimension of the netCDF
variable). Distances between elements are specified in units of
elements (the distance between internal elements that occupy
adjacent memory locations is 1 and not the element’s byte-length as
in netCDF 2).
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`
: The data values to be written. The data should be of the type
appropriate for the function called. You cannot put CHARACTER data
into a numeric variable or numeric data into a text variable. For
numeric data, if the type of data differs from the netCDF variable
type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_PUT\_VARM\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified START, COUNT, and STRIDE generate an index which is
out of range. Note that no error checking is possible on the imap
vector.
- One or more of the specified values are out of the range of values
representable by the external data type of the variable.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
The following IMAP vector maps in the trivial way a 2x3x4 netCDF
variable and an internal array of the same shape:
REAL A(2,3,4) ! same shape as netCDF variable
INTEGER IMAP(3)
DATA IMAP /1, 2, 6/ ! netCDF dimension inter-element distance
! ---------------- ----------------------
! most rapidly varying 1
! intermediate 2 (=IMAP(1)*2)
! most slowly varying 6 (=IMAP(2)*3)
Using the IMAP vector above with NF\_PUT\_VARM\_REAL obtains the same
rlt as simply using NF\_PUT\_VAR\_REAL.
Here is an example of using NF\_PUT\_VARM\_REAL to write – from a
transposed, internal array – a netCDF variable named rh which is
described by the FORTRAN declaration REAL RH(4,6) (note the size and
order of the dimensions):
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIM=2) ! rank of netCDF variable
INTEGER NCID ! netCDF ID
INTEGER STATUS ! return code
INTEGER RHID ! variable ID
INTEGER START(NDIM) ! netCDF variable start point
INTEGER COUNT(NDIM) ! size of internal array
INTEGER STRIDE(NDIM) ! netCDF variablebsampling intervals
INTEGER IMAP(NDIM) ! internal array inter-element distances
REAL RH(6,4) ! note transposition of netCDF variable dimensions
DATA START /1, 1/ ! start at first netCDF variable element
DATA COUNT /4, 6/ ! entire netCDF variable; order corresponds
! to netCDF variable -- not internal array
DATA STRIDE /1, 1/ ! sample every netCDF element
DATA IMAP /6, 1/ ! would be /1, 4/ if not transposing
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID(NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_PUT_VARM_REAL(NCID, RHID, START, COUNT, STRIDE, IMAP, RH)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
Here is another example of using NF\_PUT\_VARM\_REAL to write – from a
transposed, internal array – absample of the same netCDF variable, by
writing every other point of the netCDF variable:
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIM=2) ! rank of netCDF variable
INTEGER NCID ! netCDF dataset ID
INTEGER STATUS ! return code
INTEGER RHID ! variable ID
INTEGER START(NDIM) ! netCDF variable start point
INTEGER COUNT(NDIM) ! size of internal array
INTEGER STRIDE(NDIM) ! netCDF variablebsampling intervals
INTEGER IMAP(NDIM) ! internal array inter-element distances
REAL RH(3,2) ! note transposition of bsampled) dimensions
DATA START /1, 1/ ! start at first netCDF variable value
DATA COUNT /2, 3/ ! order of bsampled) dimensions corresponds
! to netCDF variable -- not internal array
DATA STRIDE /2, 2/ ! sample every other netCDF element
DATA IMAP /3, 1/ ! would be `1, 2' if not transposing
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID(NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_PUT_VARM_REAL(NCID, RHID, START, COUNT, STRIDE, IMAP, RH)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.24 NF\_GET\_VAR1\_ type
-------------------------
The functions NF\_GET\_VAR1\_ type get a single data value from a
variable of an open netCDF dataset that is in data mode. Inputs are the
netCDF ID, the variable ID, a multidimensional index that specifies
which value to get, and the address of a location into which the data
value will be read. The value is converted from the external data type
of the variable, if necessary.
Usage
-----
INTEGER FUNCTION NF_GET_VAR1_TEXT(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), CHARACTER CHVAL)
INTEGER FUNCTION NF_GET_VAR1_INT1(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), INTEGER*1 I1VAL)
INTEGER FUNCTION NF_GET_VAR1_INT2(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), INTEGER*2 I2VAL)
INTEGER FUNCTION NF_GET_VAR1_INT (INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), INTEGER IVAL)
INTEGER FUNCTION NF_GET_VAR1_REAL(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), REAL RVAL)
INTEGER FUNCTION NF_GET_VAR1_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), DOUBLE DVAL)
INTEGER FUNCTION NF_GET_VAR1(INTEGER NCID, INTEGER VARID,
INTEGER INDEX(*), VAL)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`INDEX`
: The index of the data value to be read. The indices are relative to
1, so for example, the first data value of a two-dimensional
variable has index (1,1). The elements of index correspond to the
variable’s dimensions. Hence, if the variable is a record variable,
the last index is the record number.
`CHVAL`\
`I1VAL`\
`I2VAL`\
`IVAL`\
`RVAL`\
`DVAL`\
`VAL`
: The location into which the data value will be read. You cannot get
CHARACTER data from a numeric variable or numeric data from a
character variable. For numeric data, if the type of data differs
from the netCDF variable type, type conversion will occur. (see
[(netcdf)Type Conversion](netcdf.html#Type-Conversion) ‘Type
Conversion’ in The NetCDF Users Guide).
Errors
------
NF\_GET\_VAR1\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified indices were out of range for the rank of the
specified variable. For example, a negative index or an index that
is larger than the corresponding dimension length will cause an
error.
- The value is out of the range of values representable by the desired
data type.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_GET\_VAR1\_DOUBLE to get the (4,3,2)
element of the variable named rh in an existing netCDF dataset named
foo.nc. For simplicity in this example, we ame that we know that rh
is dimensioned with lon, lat, and time, so we want to get the value of
rh that corresponds to the fourth lon value, the third lat value, and
the second time value:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
INTEGER RHINDX(3) ! where to get value
DOUBLE PRECISION RHVAL ! put it here
DATA RHINDX /4, 3, 2/
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_GET_VAR1_DOUBLE (NCID, RHID, RHINDX, RHVAL)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.25 NF\_GET\_VAR\_ type
------------------------
The members of the NF\_GET\_VAR\_ type family of functions read all the
values from a netCDF variable of an open netCDF dataset. This is the
simplest interface to use for reading the value of a scalar variable or
when all the values of a multidimensional variable can be read at once.
The values are read into consecutive locations with the first dimension
varying fastest. The netCDF dataset must be in data mode.
Take care when using the simplest forms of this interface with record
variables (variables that use the NF\_UNLIMITED dimension) when you
don’t specify how many records are to be read. If you try to read all
the values of a record variable into an array but there are more records
in the file than you ame, more data will be read than you expect,
which may cause a segmentation violation. To avoidch problems, it is
better to use the NF\_GET\_VARA\_type interfaces for variables that use
the NF\_UNLIMITED dimension. See [NF\_GET\_VARA\_
type](#NF_005fGET_005fVARA_005f-type).
Usage
-----
INTEGER FUNCTION NF_GET_VAR_TEXT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) text)
INTEGER FUNCTION NF_GET_VAR_INT1 (INTEGER NCID, INTEGER VARID,
INTEGER*1 i1vals(*))
INTEGER FUNCTION NF_GET_VAR_INT2 (INTEGER NCID, INTEGER VARID,
INTEGER*2 i2vals(*))
INTEGER FUNCTION NF_GET_VAR_INT (INTEGER NCID, INTEGER VARID,
INTEGER ivals(*))
INTEGER FUNCTION NF_GET_VAR_REAL (INTEGER NCID, INTEGER VARID,
REAL rvals(*))
INTEGER FUNCTION NF_GET_VAR_DOUBLE(INTEGER NCID, INTEGER VARID,
DOUBLE dvals(*))
INTEGER FUNCTION NF_GET_VAR (INTEGER NCID, INTEGER VARID,
vals(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`\
`VALS`
: The block of data values to be read. The data should be of the type
appropriate for the function called. You cannot read CHARACTER data
from a numeric variable or numeric data from a text variable. For
numeric data, if the type of data differs from the netCDF variable
type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_GET\_VAR\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- One or more of the values are out of the range of values
representable by the desired type.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_GET\_VAR\_DOUBLE to read all the values of
the variable named rh from an existing netCDF dataset named foo.nc. For
simplicity in this example, we ame that we know that rh is
dimensioned with lon and lat, and that there are ten lon values and five
lat values.
INCLUDE 'netcdf.inc'
...
PARAMETER (LATS=5, LONS=10) ! dimension lengths
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
DOUBLE RHVALS(LONS, LATS)
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_GET_VAR_DOUBLE (NCID, RHID, RHVALS)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.26 NF\_GET\_VARA\_ type
-------------------------
The members of the NF\_GET\_VARA\_ type family of functions read an
array of values from a netCDF variable of an open netCDF dataset. The
array is specified by giving a corner and a vector of edge lengths. The
values are read into consecutive locations with the first dimension
varying fastest. The netCDF dataset must be in data mode.
Usage
-----
INTEGER FUNCTION NF_GET_VARA_TEXT(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
CHARACTER*(*) text)
INTEGER FUNCTION NF_GET_VARA_INT1(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER*1 i1vals(*))
INTEGER FUNCTION NF_GET_VARA_INT2(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER*2 i2vals(*))
INTEGER FUNCTION NF_GET_VARA_INT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER ivals(*))
INTEGER FUNCTION NF_GET_VARA_REAL(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
REAL rvals(*))
INTEGER FUNCTION NF_GET_VARA_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
DOUBLE dvals(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`START`
: A vector of integers specifying the index in the variable where the
first of the data values will be read. The indices are relative to
1, so for example, the first data value of a variable would have
index (1, 1, ..., 1). The length of START must be the same as the
number of dimensions of the specified variable. The elements of
START correspond, in order, to the variable’s dimensions. Hence, if
the variable is a record variable, the last index would correspond
to the starting record number for reading the data values.
`COUNT`
: A vector of integers specifying the edge lengths along each
dimension of the block of data values to be read. To read a single
value, for example, specify COUNT as (1, 1, ..., 1). The length of
COUNT is the number of dimensions of the specified variable. The
elements of COUNT correspond, in order, to the variable’s
dimensions. Hence, if the variable is a record variable, the last
element of COUNT corresponds to a count of the number of records to
read.
Note: setting any element of the count array to zero causes the
function to exit without error, and without doing anything.
`text`\
`i1vals`\
`i2vals`\
`ivals`\
`rvals`\
`dvals`
: The block of data values to be read. The data should be of the type
appropriate for the function called. You cannot read CHARACTER data
from a numeric variable or numeric data from a text variable. For
numeric data, if the type of data differs from the netCDF variable
type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_GET\_VARA\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified corner indices were out of range for the rank of the
specified variable. For example, a negative index or an index that
is larger than the corresponding dimension length will cause an
error.
- The specified edge lengths added to the specified corner would have
referenced data out of range for the rank of the specified variable.
For example, an edge length that is larger than the corresponding
dimension length minus the corner index will cause an error.
- One or more of the values are out of the range of values
representable by the desired type.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_GET\_VARA\_DOUBLE to read all the values of
the variable named rh from an existing netCDF dataset named foo.nc. For
simplicity in this example, we ame that we know that rh is
dimensioned with lon, lat, and time, and that there are ten lon values,
five lat values, and three time values.
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIMS=3) ! number of dimensions
PARAMETER (TIMES=3, LATS=5, LONS=10) ! dimension lengths
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
INTEGER START(NDIMS), COUNT(NDIMS)
DOUBLE RHVALS(LONS, LATS, TIMES)
DATA START /1, 1, 1/ ! start at first value
DATA COUNT /LONS, LATS, TIMES/ ! get all the values
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_GET_VARA_DOUBLE (NCID, RHID, START, COUNT, RHVALS)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.27 NF\_GET\_VARS\_ type
-------------------------
The NF\_GET\_VARS\_ type family of functions read absampled (strided)
array of values from a netCDF variable of an open netCDF
dataset. Thebsampled array is specified by giving a corner, a
vector of edge lengths, and a stride vector. The values are read with
the first dimension of the netCDF variable varying fastest. The netCDF
dataset must be in data mode.
Usage
-----
INTEGER FUNCTION NF_GET_VARS_TEXT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*),CHARACTER*(*) text)
INTEGER FUNCTION NF_GET_VARS_INT1 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*),INTEGER*1 i1vals(*))
INTEGER FUNCTION NF_GET_VARS_INT2 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*),INTEGER*2 i2vals(*))
INTEGER FUNCTION NF_GET_VARS_INT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER ivals(*))
INTEGER FUNCTION NF_GET_VARS_REAL (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), REAL rvals(*))
INTEGER FUNCTION NF_GET_VARS_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), DOUBLE dvals(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`START`
: A vector of integers specifying the index in the variable from which
the first of the data values will be read. The indices are relative
to 1, so for example, the first data value of a variable would have
index (1, 1, ..., 1). The elements of START correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last index would correspond to the starting record
number for reading the data values.
`COUNT`
: A vector of integers specifying the number of indices selected along
each dimension. To read a single value, for example, specify COUNT
as (1, 1, ..., 1). The elements of COUNT correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last element of COUNT corresponds to a count of the
number of records to read.
Note: setting any element of the count array to zero causes the
function to exit without error, and without doing anything.
`STRIDE`
: A vector of integers specifying, for each dimension, the interval
between selected indices or the value 0. The elements of the vector
correspond, in order, to the variable’s dimensions. A value of 1
accesses adjacent values of the netCDF variable in the corresponding
dimension; a value of 2 accesses every other value of the netCDF
variable in the corresponding dimension; and so on. A 0 argument is
treated as (1, 1, ..., 1).
`text`\
`i1vals`\
`i2vals`\
`ivals`\
`rvals`\
`dvals`
: The block of data values to be read. The data should be of the type
appropriate for the function called. You cannot read CHARACTER data
from a numeric variable or numeric data from a text variable. For
numeric data, if the type of data differs from the netCDF variable
type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_GET\_VARS\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified start, count and stride generate an index which is out
of range.
- One or more of the values are out of the range of values
representable by the desired type.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_GET\_VARS\_DOUBLE to read every other value
in each dimension of the variable named rh from an existing netCDF
dataset named foo.nc. Values are assigned, using the same dimensional
strides, to a 2-parameter array. For simplicity in this example, we
ame that we know that rh is dimensioned with lon, lat, and time, and
that there are ten lon values, five lat values, and three time values.
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIMS=3) ! number of dimensions
PARAMETER (TIMES=3, LATS=5, LONS=10) ! dimension lengths
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
INTEGER START(NDIMS), COUNT(NDIMS), STRIDE(NDIMS)
DOUBLE DATA(LONS, LATS, TIMES)
DATA START /1, 1, 1/ ! start at first value
DATA COUNT /LONS, LATS, TIMES/
DATA STRIDE /2, 2, 2/
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_GET_VARS_DOUBLE(NCID,RHID,START,COUNT,STRIDE,DATA(1,1,1))
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.28 NF\_GET\_VARM\_ type
-------------------------
The NF\_GET\_VARM\_ type family of functions reads a mapped array
section of values from a netCDF variable of an open netCDF dataset. The
mapped array is specified by giving a corner, a vector of edge
lengths, a stride vector, and an index mapping vector. The index mapping
vector is a vector of integers that specifies the mapping between the
dimensions of a netCDF variable and the in-memory structure of the
internal data array. No amptions are made about the ordering or
length of the dimensions of the data array. The netCDF dataset must be
in data mode.
Usage
-----
INTEGER FUNCTION NF_GET_VARM_TEXT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
CHARACTER*(*) text)
INTEGER FUNCTION NF_GET_VARM_INT1 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
INTEGER*1 i1vals(*))
INTEGER FUNCTION NF_GET_VARM_INT2 (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
INTEGER*2 i2vals(*))
INTEGER FUNCTION NF_GET_VARM_INT (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
INTEGER ivals(*))
INTEGER FUNCTION NF_GET_VARM_REAL (INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
REAL rvals(*))
INTEGER FUNCTION NF_GET_VARM_DOUBLE(INTEGER NCID, INTEGER VARID,
INTEGER START(*), INTEGER COUNT(*),
INTEGER STRIDE(*), INTEGER IMAP(*),
DOUBLE dvals(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`START`
: A vector of integers specifying the index in the variable from which
the first of the data values will be read. The indices are relative
to 1, so for example, the first data value of a variable would have
index (1, 1, ..., 1). The elements of START correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last index would correspond to the starting record
number for reading the data values.
`COUNT`
: A vector of integers specifying the number of indices selected along
each dimension. To read a single value, for example, specify COUNT
as (1, 1, ..., 1). The elements of COUNT correspond, in order, to
the variable’s dimensions. Hence, if the variable is a record
variable, the last element of COUNT corresponds to a count of the
number of records to read.
Note: setting any element of the count array to zero causes the
function to exit without error, and without doing anything.
`STRIDE`
: A vector of integers specifying, for each dimension, the interval
between selected indices or the value 0. The elements of the vector
correspond, in order, to the variable’s dimensions. A value of 1
accesses adjacent values of the netCDF variable in the corresponding
dimension; a value of 2 accesses every other value of the netCDF
variable in the corresponding dimension; and so on. A 0 argument is
treated as (1, 1, ..., 1).
`IMAP`
: A vector of integers that specifies the mapping between the
dimensions of a netCDF variable and the in-memory structure of the
internal data array. IMAP(1) gives the distance between elements of
the internal array corresponding to the most rapidly varying
dimension of the netCDF variable. IMAP(N) (where N is the rank of
the netCDF variable) gives the distance between elements of the
internal array corresponding to the most slowly varying dimension of
the netCDF variable. Intervening IMAP elements correspond to other
dimensions of the netCDF variable in the obvious way. Distances
between elements are specified in units of elements (the distance
between internal elements that occupy adjacent memory locations is 1
and not the element’s byte-length as in netCDF 2).
`text`\
`i1vals`\
`i2vals`\
`ivals`\
`rvals`\
`dvals`
: The block of data values to be read. The data should be of the type
appropriate for the function called. You cannot read CHARACTER data
from a numeric variable or numeric data from a text variable. For
numeric data, if the type of data differs from the netCDF variable
type, type conversion will occur (see [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide).
Errors
------
NF\_GET\_VARM\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified START, COUNT, and STRIDE generate an index which is
out of range. Note that no error checking is possible on the imap
vector.
- One or more of the values are out of the range of values
representable by the desired type.
- The specified netCDF is in define mode rather than data mode.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
The following IMAP vector maps in the trivial way a 2x3x4 netCDF
variable and an internal array of the same shape:
REAL A(2,3,4) ! same shape as netCDF variable
INTEGER IMAP(3)
DATA IMAP /1, 2, 6/ ! netCDF dimension inter-element distance
! ---------------- ----------------------
! most rapidly varying 1
! intermediate 2 (=IMAP(1)*2)
! most slowly varying 6 (=IMAP(2)*3)
Using the IMAP vector above with NF\_GET\_VARM\_REAL obtains the same
rlt as simply using NF\_GET\_VAR\_REAL.
Here is an example of using NF\_GET\_VARM\_REAL to transpose a netCDF
variable named rh which is described by the FORTRAN declaration REAL
RH(4,6) (note the size and order of the dimensions):
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIM=2) ! rank of netCDF variable
INTEGER NCID ! netCDF dataset ID
INTEGER STATUS ! return code
INTEGER RHID ! variable ID
INTEGER START(NDIM) ! netCDF variable start point
INTEGER COUNT(NDIM) ! size of internal array
INTEGER STRIDE(NDIM) ! netCDF variablebsampling intervals
INTEGER IMAP(NDIM) ! internal array inter-element distances
REAL RH(6,4) ! note transposition of netCDF variable dimensions
DATA START /1, 1/ ! start at first netCDF variable element
DATA COUNT /4, 6/ ! entire netCDF variable; order corresponds
! to netCDF variable -- not internal array
DATA STRIDE /1, 1/ ! sample every netCDF element
DATA IMAP /6, 1/ ! would be /1, 4/ if not transposing
...
STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID(NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_GET_VARM_REAL(NCID, RHID, START, COUNT, STRIDE, IMAP, RH)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
Here is another example of using NF\_GET\_VARM\_REAL to simultaneously
transpose andbsample the same netCDF variable, by accessing every
other point of the netCDF variable:
INCLUDE 'netcdf.inc'
...
PARAMETER (NDIM=2) ! rank of netCDF variable
INTEGER NCID ! netCDF dataset ID
INTEGER STATUS ! return code
INTEGER RHID ! variable ID
INTEGER START(NDIM) ! netCDF variable start point
INTEGER COUNT(NDIM) ! size of internal array
INTEGER STRIDE(NDIM) ! netCDF variablebsampling intervals
INTEGER IMAP(NDIM) ! internal array inter-element distances
REAL RH(3,2) ! note transposition of bsampled) dimensions
DATA START /1, 1/ ! start at first netCDF variable value
DATA COUNT /2, 3/ ! order of bsampled) dimensions corresponds
! to netCDF variable -- not internal array
DATA STRIDE /2, 2/ ! sample every other netCDF element
DATA IMAP /3, 1/ ! would be `1, 2' if not transposing
...
STATUS = NF_OPEN('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID(NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_GET_VARM_REAL(NCID, RHID, START, COUNT, STRIDE, IMAP, RH)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.29 Reading and Writing Character String Values
------------------------------------------------
Character strings are not a primitive netCDF external data type, in part
because FORTRAN does notpport the abstraction of variable-length
character strings (the FORTRAN LEN function returns the static length of
a character string, not its dynamic length). As a rlt, a character
string cannot be written or read as a single object in the netCDF
interface. Instead, a character string must be treated as an array of
characters, and array access must be used to read and write character
strings as variable data in netCDF datasets. Furthermore,
variable-length strings are notpported by the netCDF interface except
by convention; for example, you may treat a zero byte as terminating a
character string, but you must explicitly specify the length of strings
to be read from and written to netCDF variables.
Character strings as attribute values are easier to use, since the
strings are treated as a single unit for access. However, the value of a
character-string attribute is still an array of characters with an
explicit length that must be specified when the attribute is defined.
When you define a variable that will have character-string values, use a
character-position dimension as the most quickly varying dimension for
the variable (the first dimension for the variable in FORTRAN). The
length of the character-position dimension will be the maximum string
length of any value to be stored in the character-string variable. Space
for maximum-length strings will be allocated in the disk representation
of character-string variables whether you use the space or not. If two
or more variables have the same maximum length, the same
character-position dimension may be used in defining the variable
shapes.
To write a character-string value into a character-string variable, use
either entire variable access or array access. The latter requires that
you specify both a corner and a vector of edge lengths. The
character-position dimension at the corner should be one for FORTRAN. If
the length of the string to be written is n, then the vector of edge
lengths will specify n in the character-position dimension, and one for
all the other dimensions:(n, 1, 1, ..., 1).
In FORTRAN, fixed-length strings may be written to a netCDF dataset
without a terminating character, to save space. Variable-length strings
should follow the C convention of writing strings with a terminating
zero byte so that the intended length of the string can be determined
when it is later read by either C or FORTRAN programs.
The FORTRAN interface for reading and writing strings requires the use
of different functions for accessing string values and numeric values,
because standard FORTRAN does not permit the same formal parameter to be
used for both character values and numeric values. An additional
argument, specifying the declared length of the character string passed
as a value, is required for NF\_PUT\_VARA\_TEXT and NF\_GET\_VARA\_TEXT.
The actual length of the string is specified as the value of the
edge-length vector corresponding to the character-position dimension.
Here is an example that defines a record variable, tx, for character
strings and stores a character-string value into the third record using
NF\_PUT\_VARA\_TEXT. In this example, we ame the string variable and
data are to be added to an existing netCDF dataset named foo.nc that
already has an unlimited record dimension time.
INCLUDE 'netcdf.inc'
...
INTEGER TDIMS, TXLEN
PARAMETER (TDIMS=2) ! number of TX dimensions
PARAMETER (TXLEN = 15) ! length of example string
INTEGER NCID
INTEGER CHID ! char position dimension id
INTEGER TIMEID ! record dimension id
INTEGER TXID ! variable ID
INTEGER TXDIMS(TDIMS) ! variable shape
INTEGER TSTART(TDIMS), TCOUNT(TDIMS)
CHARACTER*40 TXVAL ! max length 40
DATA TXVAL /'example string'/
...
TXVAL(TXLEN:TXLEN) = CHAR(0) ! null terminate
...
STATUS = NF_OPEN('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_REDEF(NCID) ! enter define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! define character-position dimension for strings of max length 40
STATUS = NF_DEF_DIM(NCID, "chid", 40, CHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! define a character-string variable
TXDIMS(1) = CHID ! character-position dimension first
TXDIMS(2) = TIMEID
STATUS = NF_DEF_VAR(NCID, "tx", NF_CHAR, TDIMS, TXDIMS, TXID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_ENDDEF(NCID) ! leave define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! write txval into tx netCDF variable in record 3
TSTART(1) = 1 ! start at beginning of variable
TSTART(2) = 3 ! record number to write
TCOUNT(1) = TXLEN ! number of chars to write
TCOUNT(2) = 1 ! only write one record
STATUS = NF_PUT_VARA_TEXT (NCID, TXID, TSTART, TCOUNT, TXVAL)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.30 Fill Values
----------------
What happens when you try to read a value that was never written in an
open netCDF dataset? You might expect that this should always be an
error, and that you should get an error message or an error status
returned. You do get an error if you try to read data from a netCDF
dataset that is not open for reading, if the variable ID is invalid for
the specified netCDF dataset, or if the specified indices are not
properly within the range defined by the dimension lengths of the
specified variable. Otherwise, reading a value that was not written
returns a special fill value used to fill in any undefined values when a
netCDF variable is first written.
You may ignore fill values and use the entire range of a netCDF external
data type, but in this case you should makere you write all data
values before reading them. If you know you will be writing all the data
before reading it, you can specify that no prefilling of variables with
fill values will occur by calling NF\_SET\_FILL before writing. This may
provide a significant performance gain for netCDF writes.
The variable attribute \_FillValue may be used to specify the fill value
for a variable. Their are default fill values for each type, defined in
the include file netcdf.inc: NF\_FILL\_CHAR, NF\_FILL\_INT1 (same as
NF\_FILL\_BYTE), NF\_FILL\_INT2 (same as NF\_FILL\_SHORT),
NF\_FILL\_INT, NF\_FILL\_REAL (same as NF\_FILL\_FLOAT), and
NF\_FILL\_DOUBLE.
The netCDF byte and character types have different default fill values.
The default fill value for characters is the zero byte, a useful value
for detecting the end of variable-length C character strings. If you
need a fill value for a byte variable, it is recommended that you
explicitly define an appropriate \_FillValue attribute, as generic
utilitiesch as ncdump will not ame a default fill value for byte
variables.
Type conversion for fill values is identical to type conversion for
other values: attempting to convert a value from one type to another
type that can’t represent the value rlts in a range error. Such
errors may occur on writing or reading values from a larger type ch
as double) to a smaller type ch as float), if the fill value for the
larger type cannot be represented in the smaller type.
6.31 NF\_RENAME\_VAR
--------------------
The function NF\_RENAME\_VAR changes the name of a netCDF variable in an
open netCDF dataset. If the new name is longer than the old name, the
netCDF dataset must be in define mode. You cannot rename a variable to
have the name of any existing variable.
Usage
-----
INTEGER FUNCTION NF_RENAME_VAR (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NEWNAM)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID.
`NAME`
: New name for the specified variable.
Errors
------
NF\_RENAME\_VAR returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The new name is in use as the name of another variable.
- The variable ID is invalid for the specified netCDF dataset.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_RENAME\_VAR to rename the variable rh to
rel\_hum in an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_REDEF (NCID) ! enter definition mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_RENAME_VAR (NCID, RHID, 'rel_hum')
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_ENDDEF (NCID) ! leave definition mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
6.32 Change between Collective and Independent Parallel Access: NF\_VAR\_PAR\_ACCESS
------------------------------------------------------------------------------------
The function NF\_VAR\_PAR\_ACCESS changes whether read/write operations
on a parallel file system are performed collectively or independently
(the default) on the variable. This function can only be called if the
file was created with NF\_CREATE\_PAR (see
[NF\_CREATE\_PAR](#NF_005fCREATE_005fPAR)) or opened with NF\_OPEN\_PAR
(see [NF\_OPEN\_PAR](#NF_005fOPEN_005fPAR)).
This function is only available if the netCDF library was built with a
HDF5 library for which –enable-parallel was used, and which was linked
(like HDF5) to MPI libraries.
Calling this function affects only the open file - information about
whether a variable is to be accessed collectively or independently is
not written to the data file. Every time you open a file on a parallel
file system, all variables default to independent operations. The change
a variable to collective lasts only as long as that file is open.
The variable can be changed from collective to independent, and back, as
often as desired.
Usage
-----
INTEGER NF_VAR_PAR_ACCESS(INTEGER NCID, INTEGER VARID, INTEGER ACCESS);
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN\_PAR (see
[NF\_OPEN\_PAR](#NF_005fOPEN_005fPAR)) or NF\_CREATE\_PAR (see
[NF\_CREATE\_PAR](#NF_005fCREATE_005fPAR)).
`varid`
: Variable ID.
`access`
: NF\_INDEPENDENT to set this variable to independent operations.
NF\_COLLECTIVE to set it to collective operations.
Return Values
-------------
`NF_NOERR`
: No error.
`NF_ENOTVAR`
: No variable found.
`NF_ENOTNC4`
: Not a netCDF-4 file.
`NF_NOPAR`
: File not opened for parallel access.
Example
-------
This example comes from test program nf\_test/ftst\_parallel.F. For this
test to be run, netCDF must have been built with a parallel-enabled
HDF5, and –enable-parallel-tests must have been used when configuring
netcdf.
retval = nf_var_par_access(ncid, varid, nf_collective)
if (retval .ne. nf_noerr) stop 2
7. Attributes
=============
7.1 Attributes Introduction
---------------------------
Attributes may be associated with each netCDF variable to specifych
properties as units, special values, maximum and minimum valid values,
scaling factors, and offsets. Attributes for a netCDF dataset are
defined when the dataset is first created, while the netCDF dataset is
in define mode. Additional attributes may be added later by reentering
define mode. A netCDF attribute has a netCDF variable to which it is
assigned, a name, a type, a length, and a sequence of one or more
values. An attribute is designated by its variable ID and name. When an
attribute name is not known, it may be designated by its variable ID and
number in order to determine its name, using the function
NF\_INQ\_ATTNAME.
The attributes associated with a variable are typically defined
immediately after the variable is created, while still in define mode.
The data type, length, and value of an attribute may be changed even
when in data mode, as long as the changed attribute requires no more
space than the attribute as originally defined.
It is also possible to have attributes that are not associated with any
variable. These are called global attributes and are identified by using
NF\_GLOBAL as a variable pseudo-ID. Global attributes are ally
related to the netCDF dataset as a whole and may be used for purposes
such as providing a title or processing history for a netCDF dataset.
Attributes are much more useful when they follow established community
conventions. See [(netcdf)Attribute
Conventions](netcdf.html#Attribute-Conventions) ‘Attribute
Conventions’ in The NetCDF Users Guide.
Operationspported on attributes are:
- Create an attribute, given its variable ID, name, data type, length,
and value.
- Get attribute’s data type and length from its variable ID and name.
- Get attribute’s value from its variable ID and name.
- Copy attribute from one netCDF variable to another.
- Get name of attribute from its number.
- Rename an attribute.
- Delete an attribute.
7.2 NF\_PUT\_ATT\_ type
-----------------------
The function NF\_PUT\_ATT\_ type adds or changes a variable attribute or
global attribute of an open netCDF dataset. If this attribute is new, or
if the space required to store the attribute is greater than before, the
netCDF dataset must be in define mode.
Usage
-----
Although it’s possible to create attributes of all types, text and
double attributes are adequate for most purposes.
INTEGER FUNCTION NF_PUT_ATT_TEXT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER LEN,
CHARACTER*(*) TEXT)
INTEGER FUNCTION NF_PUT_ATT_INT1 (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER XTYPE,
LEN, INTEGER*1 I1VALS(*))
INTEGER FUNCTION NF_PUT_ATT_INT2 (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER XTYPE,
LEN, INTEGER*2 I2VALS(*))
INTEGER FUNCTION NF_PUT_ATT_INT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER XTYPE,
LEN, INTEGER IVALS(*))
INTEGER FUNCTION NF_PUT_ATT_REAL (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER XTYPE,
LEN, REAL RVALS(*))
INTEGER FUNCTION NF_PUT_ATT_DOUBLE(INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER XTYPE,
LEN, DOUBLE DVALS(*))
INTEGER FUNCTION NF_PUT_ATT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER XTYPE,
LEN, * VALS(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID of the variable to which the attribute will be assigned
or NF\_GLOBAL for a global attribute.
`NAME`
: Attribute name. Attribute name conventions are amed by some
netCDF generic applications, e.g., ‘units’ as the name for a string
attribute that gives the units for a netCDF variable. See
[(netcdf)Attribute Conventions](netcdf.html#Attribute-Conventions)
‘Attribute Conventions’ in The NetCDF Users Guide.
`XTYPE`
: One of the set of predefined netCDF external data types. The type of
this parameter, NF\_TYPE, is defined in the netCDF header file. The
valid netCDF external data types are NF\_BYTE, NF\_CHAR, NF\_SHORT,
NF\_INT, NF\_FLOAT, and NF\_DOUBLE. Although it’s possible to create
attributes of all types, NF\_CHAR and NF\_DOUBLE attributes are
adequate for most purposes.
`LEN`
: Number of values provided for the attribute.
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`\
`VALS`
: An array of LEN attribute values. The data should be of a type
appropriate for the function called. You cannot write CHARACTER data
into a numeric attribute or numeric data into a text attribute. For
numeric data, if the type of data differs from the attribute type,
type conversion will occur See [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The NetCDF Users Guide.
Errors
------
NF\_PUT\_ATT\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified netCDF type is invalid.
- The specified length is negative.
- The specified open netCDF dataset is in data mode and the specified
attribute would expand.
- The specified open netCDF dataset is in data mode and the specified
attribute does not already exist.
- The specified netCDF ID does not refer to an open netCDF dataset.
- The number of attributes for this variable exceeds NF\_MAX\_ATTRS.
Example
-------
Here is an example using NF\_PUT\_ATT\_DOUBLE to add a variable
attribute named valid\_range for a netCDF variable named rh and a global
attribute named title to an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
DOUBLE RHRNGE(2)
DATA RHRNGE /0.0D0, 100.0D0/
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_REDEF (NCID) ! enter define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_PUT_ATT_DOUBLE (NCID, RHID, 'valid_range', NF_DOUBLE, &
2, RHRNGE)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_PUT_ATT_TEXT (NCID, NF_GLOBAL, 'title', 19,
'example netCDF dataset')
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_ENDDEF (NCID) ! leave define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
7.3 NF\_INQ\_ATT Family
-----------------------
This family of functions returns information about a netCDF attribute.
All but one of these functions require the variable ID and attribute
name; the exception is NF\_INQ\_ATTNAME. Information about an attribute
includes its type, length, name, and number. See the NF\_GET\_ATT family
for getting attribute values.
The function NF\_INQ\_ATTNAME gets the name of an attribute, given its
variable ID and number. This function is useful in generic applications
that need to get the names of all the attributes associated with a
variable, since attributes are accessed by name rather than number in
all other attribute functions. The number of an attribute is more
volatile than the name, since it can change when other attributes of the
same variable are deleted. This is why an attribute number is not called
an attribute ID.
The function NF\_INQ\_ATT returns the attribute’s type and length. The
other functions each return just one item of information about an
attribute.
Usage
-----
INTEGER FUNCTION NF_INQ_ATT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER xtype,
INTEGER len)
INTEGER FUNCTION NF_INQ_ATTTYPE(INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER xtype)
INTEGER FUNCTION NF_INQ_ATTLEN (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER len)
INTEGER FUNCTION NF_INQ_ATTNAME(INTEGER NCID, INTEGER VARID,
INTEGER ATTNUM, CHARACTER*(*) name)
INTEGER FUNCTION NF_INQ_ATTID (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, INTEGER attnum)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID of the attribute’s variable, or NF\_GLOBAL for a global
attribute.
`NAME`
: Attribute name. For NF\_INQ\_ATTNAME, this is a pointer to the
location for the returned attribute name.
`xtype`
: Returned attribute type, one of the set of predefined netCDF
external data types. The valid netCDF external data types are
NF\_BYTE, NF\_CHAR, NF\_SHORT, NF\_INT, NF\_FLOAT, and NF\_DOUBLE.
`len`
: Returned number of values currently stored in the attribute. For a
string-valued attribute, this is the number of characters in the
string.
`attnum`
: For NF\_INQ\_ATTNAME, the input attribute number; for
NF\_INQ\_ATTID, the returned attribute number. The attributes for
each variable are numbered from 1 (the first attribute) to NATTS,
where NATTS is the number of attributes for the variable, as
returned from a call to NF\_INQ\_VARNATTS.
(If you already know an attribute name, knowing its number is not
very useful, because accessing information about an attribute
requires its name.)
Errors
------
Each function returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified attribute does not exist.
- The specified netCDF ID does not refer to an open netCDF dataset.
- For NF\_INQ\_ATTNAME, the specified attribute number is negative or
more than the number of attributes defined for the specified
variable.
Example
-------
Here is an example using NF\_INQ\_ATT to find out the type and length of
a variable attribute named valid\_range for a netCDF variable named rh
and a global attribute named title in an existing netCDF dataset named
foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
INTEGER VRLEN, TLEN ! attribute lengths
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_ATTLEN (NCID, RHID, 'valid_range', VRLEN)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_ATTLEN (NCID, NF_GLOBAL, 'title', TLEN)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
7.4 NF\_GET\_ATT\_ type
-----------------------
Members of the NF\_GET\_ATT\_ type family of functions get the value(s)
of a netCDF attribute, given its variable ID and name.
Usage
-----
INTEGER FUNCTION NF_GET_ATT_TEXT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
CHARACTER*(*) text)
INTEGER FUNCTION NF_GET_ATT_INT1 (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
INTEGER*1 i1vals(*))
INTEGER FUNCTION NF_GET_ATT_INT2 (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
INTEGER*2 i2vals(*))
INTEGER FUNCTION NF_GET_ATT_INT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
INTEGER ivals(*))
INTEGER FUNCTION NF_GET_ATT_REAL (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
REAL rvals(*))
INTEGER FUNCTION NF_GET_ATT_DOUBLE (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
DOUBLE dvals(*))
INTEGER FUNCTION NF_GET_ATT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME, * vals(*))
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: Variable ID of the attribute’s variable, or NF\_GLOBAL for a global
attribute.
`NAME`
: Attribute name.
`TEXT`\
`I1VALS`\
`I2VALS`\
`IVALS`\
`RVALS`\
`DVALS`\
`VALS`
: Returned attribute values. All elements of the vector of attribute
values are returned, so you must provide enough space to hold them.
If you don’t know how much space to reserve, call NF\_INQ\_ATTLEN
first to find out the length of the attribute. You cannot read
character data from a numeric variable or numeric data from a text
variable. For numeric data, if the type of data differs from the
netCDF variable type, type conversion will occur. See [(netcdf)Type
Conversion](netcdf.html#Type-Conversion) ‘Type Conversion’
in The The NetCDF Users Guide.
Errors
------
NF\_GET\_ATT\_ type returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The variable ID is invalid for the specified netCDF dataset.
- The specified attribute does not exist.
- The specified netCDF ID does not refer to an open netCDF dataset.
- One or more of the attribute values are out of the range of values
representable by the desired type.
Example
-------
Here is an example using NF\_GET\_ATT\_DOUBLE to determine the values of
a variable attribute named valid\_range for a netCDF variable named rh
and a global attribute named title in an existing netCDF dataset named
foo.nc. In this example, it is amed that we don’t know how many
values will be returned, but that we do know the types of the
attributes. Hence, to allocate enough space to store them, we must first
inquire about the length of the attributes.
INCLUDE 'netcdf.inc'
...
PARAMETER (MVRLEN=3) ! max number of "valid_range" values
PARAMETER (MTLEN=80) ! max length of "title" attribute
INTEGER STATUS, NCID
INTEGER RHID ! variable ID
INTEGER VRLEN, TLEN ! attribute lengths
DOUBLE PRECISION VRVAL(MVRLEN) ! vr attribute values
CHARACTER*80 TITLE ! title attribute values
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! find out attribute lengths, to makere we have enough space
STATUS = NF_INQ_ATTLEN (NCID, RHID, 'valid_range', VRLEN)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_ATTLEN (NCID, NF_GLOBAL, 'title', TLEN)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
! get attribute values, if not too big
IF (VRLEN .GT. MVRLEN) THEN
WRITE (*,*) 'valid_range attribute too big!'
CALL EXIT
ELSE
STATUS = NF_GET_ATT_DOUBLE (NCID, RHID, 'valid_range', VRVAL)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
ENDIF
IF (TLEN .GT. MTLEN) THEN
WRITE (*,*) 'title attribute too big!'
CALL EXIT
ELSE
STATUS = NF_GET_ATT_TEXT (NCID, NF_GLOBAL, 'title', TITLE)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
ENDIF
7.5 NF\_COPY\_ATT
-----------------
The function NF\_COPY\_ATT copies an attribute from one open netCDF
dataset to another. It can also be used to copy an attribute from one
variable to another within the same netCDF.
If used to copy an attribute of user-defined type, then that
user-defined type must already be defined in the target file. In the
case of user-defined attributes, enddef/redef is called for ncid\_in and
ncid\_out if they are in define mode. (This is the ere that all
user-defined types are committed to the file(s) before the copy is
attempted.)
Usage
-----
INTEGER FUNCTION NF_COPY_ATT (INTEGER NCID_IN, INTEGER VARID_IN,
CHARACTER*(*) NAME, INTEGER NCID_OUT,
INTEGER VARID_OUT)
`NCID_IN`
: The netCDF ID of an input netCDF dataset from which the attribute
will be copied, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID_IN`
: ID of the variable in the input netCDF dataset from which the
attribute will be copied, or NF\_GLOBAL for a global attribute.
`NAME`
: Name of the attribute in the input netCDF dataset to be copied.
`NCID_OUT`
: The netCDF ID of the output netCDF dataset to which the attribute
will be copied, from a previous call to NF\_OPEN or NF\_CREATE. It
is permissible for the input and output netCDF IDs to be the same.
The output netCDF dataset should be in define mode if the attribute
to be copied does not already exist for the target variable, or if
it would cause an existing target attribute to grow.
`VARID_OUT`
: ID of the variable in the output netCDF dataset to which the
attribute will be copied, or NF\_GLOBAL to copy to a global
attribute.
Errors
------
NF\_COPY\_ATT returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The input or output variable ID is invalid for the specified netCDF
dataset.
- The specified attribute does not exist.
- The output netCDF is not in define mode and the attribute is new for
the output dataset is larger than the existing attribute.
- The input or output netCDF ID does not refer to an open netCDF
dataset.
Example
-------
Here is an example using NF\_COPY\_ATT to copy the variable attribute
units from the variable rh in an existing netCDF dataset named foo.nc to
the variable avgrh in another existing netCDF dataset named bar.nc,
aming that the variable avgrh already exists, but does not yet have a
units attribute:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS ! error status
INTEGER NCID1, NCID2 ! netCDF IDs
INTEGER RHID, AVRHID ! variable IDs
...
STATUS = NF_OPEN ('foo.nc', NF_NOWRITE, NCID1)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_OPEN ('bar.nc', NF_WRITE, NCID2)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID1, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_INQ_VARID (NCID2, 'avgrh', AVRHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_REDEF (NCID2) ! enter define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
! copy variable attribute from "rh" to "avgrh"
STATUS = NF_COPY_ATT (NCID1, RHID, 'units', NCID2, AVRHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_ENDDEF (NCID2) ! leave define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
7.6 NF\_RENAME\_ATT
-------------------
The function NF\_RENAME\_ATT changes the name of an attribute. If the
new name is longer than the original name, the netCDF dataset must be in
define mode. You cannot rename an attribute to have the same name as
another attribute of the same variable.
Usage
-----
INTEGER FUNCTION NF_RENAME_ATT (INTEGER NCID, INTEGER VARID,
CHARACTER*(*) NAME,
CHARACTER*(*) NEWNAME)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE
`VARID`
: ID of the attribute’s variable, or NF\_GLOBAL for a global attribute
`NAME`
: The current attribute name.
`NEWNAME`
: The new name to be assigned to the specified attribute. If the new
name is longer than the current name, the netCDF dataset must be in
define mode.
Errors
------
NF\_RENAME\_ATT returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The specified variable ID is not valid.
- The new attribute name is already in use for another attribute of
the specified variable.
- The specified netCDF dataset is in data mode and the new name is
longer than the old name.
- The specified attribute does not exist.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_RENAME\_ATT to rename the variable
attribute units to Units for a variable rh in an existing netCDF dataset
named foo.nc:
INCLUDE "netcdf.inc"
...
INTEGER STATUS ! error status
INTEGER NCID ! netCDF ID
INTEGER RHID ! variable ID
...
STATUS = NF_OPEN ("foo.nc", NF_NOWRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, "rh", RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! rename attribute
STATUS = NF_RENAME_ATT (NCID, RHID, "units", "Units")
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
7.7 NF\_DEL\_ATT
----------------
The function NF\_DEL\_ATT deletes a netCDF attribute from an open netCDF
dataset. The netCDF dataset must be in define mode.
Usage
-----
INTEGER FUNCTION NF\_DEL\_ATT (INTEGER NCID, INTEGER VARID,
CHARACTER\*(\*) NAME)
`NCID`
: NetCDF ID, from a previous call to NF\_OPEN or NF\_CREATE.
`VARID`
: ID of the attribute’s variable, or NF\_GLOBAL for a global
attribute.
`NAME`
: The name of the attribute to be deleted.
Errors
------
NF\_DEL\_ATT returns the value NF\_NOERR if no errors occurred.
Otherwise, the returned status indicates an error. Possible causes of
errors include:
- The specified variable ID is not valid.
- The specified netCDF dataset is in data mode.
- The specified attribute does not exist.
- The specified netCDF ID does not refer to an open netCDF dataset.
Example
-------
Here is an example using NF\_DEL\_ATT to delete the variable attribute
Units for a variable rh in an existing netCDF dataset named foo.nc:
INCLUDE 'netcdf.inc'
...
INTEGER STATUS ! error status
INTEGER NCID ! netCDF ID
INTEGER RHID ! variable ID
...
STATUS = NF_OPEN ('foo.nc', NF_WRITE, NCID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
STATUS = NF_INQ_VARID (NCID, 'rh', RHID)
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
...
! delete attribute
STATUS = NF_REDEF (NCID) ! enter define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_DEL_ATT (NCID, RHID, 'Units')
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
STATUS = NF_ENDDEF (NCID) ! leave define mode
IF (STATUS .NE. NF_NOERR) CALL HANDLE_ERR(STATUS)
A. NetCDF 2 to NetCDF 3 Fortran 77 Transition Guide {#f77_nc2_to_nc3_transition_guide}
===================================================
A.1 Overview of FORTRAN interface changes {#f77_overview_of_interface_changes}
-----------------------------------------
NetCDF version 3 includes a complete rewrite of the netCDF library. It
is about twice as fast as the previous version. The netCDF file format
is unchanged, so files written with version 3 can be read with version 2
code and vice versa.
The core library is now written in ANSI C. You must have an ANSI C
compiler to compile this version. The FORTRAN interface is layered on
top of the C interface using a different technique than was used in
netCDF-2.
Rewriting the library offered an opportunity to implement improved C and
FORTRAN interfaces that provide some significant benefits:
- type safety, by eliminating the need to use type punning in
arguments;
- automatic type conversions, by eliminating the undesirable coupling
between the language-independent external netCDF types (NF\_BYTE,
..., NF\_DOUBLE) and language-dependent internal data types (INT\*1,
..., DOUBLE PRECISION);
- pport for future enhancements, by eliminating obstacles to the
clean addition ofpport for packed data and multithreading;
- more standard error behavior, by uniformly communicating an error
status back to the calling program in the return value of each
function.
It is not necessary to rewrite programs that use the version 2 FORTRAN
interface, because the netCDF-3 library includes a backward
compatibility interface thatpports all the old functions, globals,
and behavior. We are hoping that the benefits of the new interface will
be an incentive to use it in new netCDF applications. It is possible to
convert old applications to the new interface incrementally, replacing
netCDF-2 calls with the corresponding netCDF-3 calls one at a time.
Other changes in the implementation of netCDF rlt in improved
portability, maintainability, and performance on most platforms. A clean
separation between I/O and type layers facilitates platform-specific
optimizations. The new library no longer uses a vendor-provided XDR
library, which simplifies linking programs that use netCDF and speeds up
data access significantly in most cases.
A.2 The New FORTRAN Interface {#f77_new_fortran_interface}
-----------------------------
First, here’s an example of FORTRAN code that uses the netCDF-2
interface:
! Use a buffer big enough for values of any type
DOUBLE PRECISION DBUF(NDATA)
REAL RBUF(NDATA)
...
EQUIVALENCE (RBUF, DBUF), ...
INT XTYPE ! to hold the actual type of the data
INT STATUS ! for error status
! Get the actual data type
CALL NCVINQ(NCID, VARID, ...,XTYPE, ...)
...
! Get the data
CALL NCVGT(NCID, VARID, START, COUNT, DBUF, STATUS)
IF(STATUS .NE. NCNOERR) THEN
PRINT *, 'Cannot get data, error code =', STATUS
! Deal with error
...
ENDIF
IF (XTYPE .EQ. NCDOUBLE) THEN
CALL DANALYZE(DBUF)
ELSEIF (XTYPE .EQ. NCFLOAT) THEN
CALL RANALYZE(RBUF)
...
ENDIF
Here’s how you might handle this with the new netCDF-3 FORTRAN
interface:
! I want to use doubles for my analysis
DOUBLE PRECISION DBUF(NDATA)
INT STATUS
! So I use a function that gets the data as doubles.
STATUS = NF_GET_VARA_DOUBLE(NCID, VARID, START, COUNT, DBUF)
IF(STATUS .NE. NF_NOERR) THEN
PRINT *, 'Cannot get data, ', NF_STRERROR(STATUS)
! Deal with error
...
ENDIF
CALL DANALYZE(DBUF)
The example above illustrates changes in function names, data type
conversion, and error handling, discussed in detail in thes
below.
A.3 Function Naming Conventions {#f77_function_naming_conventions}
-------------------------------
The netCDF-3 Fortran 77 library employs a naming convention intended to
make netCDF programs more readable. For example, the name of the
function to rename a variable is now NF\_RENAME\_VAR instead of the
previous NCVREN.
All netCDF-3 FORTRAN function names begin with the NF\_ prefix. The
second part of the name is a verb, like GET, PUT, INQ (for inquire), or
OPEN. The third part of the name is typically the object of the verb:
for example DIM, VAR, or ATT for functions dealing with dimensions,
variables, or attributes. To distinguish the various I/O operations for
variables, a single character modifier is appended to VAR:
- VAR entire variable access
- VAR1 single value access
- VARA array or array access
- VARS strided access to absample of values
- VARM mapped access to values not contiguous in memory
At the end of the name for variable and attribute functions, there is a
component indicating the type of the final argument: TEXT, INT1, INT2,
INT, REAL, or DOUBLE. This part of the function name indicates the type
of the data container you are using in your program: character string,
1-byte integer, and so on.
Also, all PARAMETER names in the public FORTRAN interface begin with the
prefix NF\_. For example, the PARAMETER which was formerly MAXNCNAM is
now NF\_MAX\_NAME, and the former FILFLOAT is now NF\_FILL\_FLOAT.
As previously mentioned, all the old names are stillpported for
backward compatibility.
A.4 Type Conversion {#f77_type_conversion}
-------------------
With the new interface, users need not be aware of the external type of
numeric variables, since automatic conversion to or from any desired
numeric type is now available. You can use this feature to simplify
code, by making it independent of external types. The elimination of
type punning prevents some kinds of type errors that could occur with
the previous interface. Programs may be made more robust with the new
interface, because they need not be changed to accommodate a change to
the external type of a variable.
If conversion to or from an external numeric type is necessary, it is
handled by the library. This automatic conversion and separation of
external data representation from internal data types will become even
more important in netCDF version 4, when new external types will be
added for packed data for which there is no natural corresponding
internal type, for example, arrays of 11-bit values.
Converting from one numeric type to another may rlt in an error if
the target type is not capable of representing the converted value. (In
netCDF-2,ch overflows can only happen in the XDR layer.) For example,
a REAL may not be able to hold data stored externally as an NF\_DOUBLE
(an IEEE floating-point number). When accessing an array of values, an
NF\_ERANGE error is returned if one or more values are out of the range
of representable values, but other values are converted properly.
Note that mere loss of precision in type conversion does not return an
error. Thus, if you read double precision values into an INTEGER, for
example, no error rlts unless the magnitude of the double precision
value exceeds the representable range of INTEGERs on your platform.
Similarly, if you read a large integer into a REAL incapable of
representing all the bits of the integer in its mantissa, this loss
There are two new functions in netCDF-3 that don’t correspond to any
netCDF-2 functions: NF\_INQ\_LIBVERS and NF\_STRERROR. The version ation
The previous implementation returned an error when the same dimension
was used more than once in specifying the shape of a variable in
ncvardef. This restriction is relaxed in the netCDF-3 implementation,
because an autocorrelation matrix is a good example where using the same
dimension twice makes sense.
In the new interface, units for the IMAP argument to the NF\_PUT\_VARM
and NF\_GET\_VARM families of functions are now in terms of the number
of data elements of the desired internal type, not in terms of bytes as
in the netCDF version-2 mapped access interfaces.
Following is a table of netCDF-2 function names and names of the
corresponding netCDF-3 functions. For parameter lists of netCDF-2
functions, see the netCDF-2 User’s Guide.
`NCABOR`
: NF\_ABORT
`NCACPY`
: NF\_COPY\_ATT
`NCADEL`
: NF\_DEL\_ATT
`NCAGT`
: NF\_GET\_ATT\_DOUBLE, NF\_GET\_ATT\_REAL, NF\_GET\_ATT\_INT,
NF\_GET\_ATT\_INT1, NF\_GET\_ATT\_INT2
`NCAGTC`
: NF\_GET\_ATT\_TEXT
`NCAINQ`
: NF\_INQ\_ATT, NF\_INQ\_ATTID, NF\_INQ\_ATTLEN, NF\_INQ\_ATTTYPE
`NCANAM`
: NF\_INQ\_ATTNAME
`NCAPT`
: NF\_PUT\_ATT\_DOUBLE, NF\_PUT\_ATT\_REAL, NF\_PUT\_ATT\_INT,
NF\_PUT\_ATT\_INT1NF\_PUT
B. Summary of FORTRAN 77 Interface {#f77_interface_summary}
==================================
Input parameters are in upper case, output parameters are in lower case.
The FORTRAN types of all the parameters are listed alphabetically by
parameter name below the function declarations.
~~~~
CHARACTER*80 FUNCTION NF_INQ_LIBVERS()
CHARACTER*80 FUNCTION NF_STRERROR (NCERR)
INTEGER FUNCTION NF_CREATE (PATH, CMODE, ncid)
INTEGER FUNCTION NF_OPEN (PATH, MODE, ncid)
INTEGER FUNCTION NF_SET_FILL (NCID, FILLMODE, old_mode)
INTEGER FUNCTION NF_REDEF (NCID)
INTEGER FUNCTION NF_ENDDEF (NCID)
INTEGER FUNCTION NF_SYNC (NCID)
INTEGER FUNCTION NF_ABORT (NCID)
INTEGER FUNCTION NF_CLOSE (NCID)
INTEGER FUNCTION NF_INQ (NCID, ndims, nvars, ngatts,
unlimdimid)
INTEGER FUNCTION NF_INQ_NDIMS (NCID, ndims)
INTEGER FUNCTION NF_INQ_NVARS (NCID, nvars)
INTEGER FUNCTION NF_INQ_NATTS (NCID, ngatts)
INTEGER FUNCTION NF_INQ_UNLIMDIM (NCID, unlimdimid)
INTEGER FUNCTION NF_DEF_DIM (NCID, NAME, LEN, dimid)
INTEGER FUNCTION NF_INQ_DIMID (NCID, NAME, dimid)
INTEGER FUNCTION NF_INQ_DIM (NCID, DIMID, name, len)
INTEGER FUNCTION NF_INQ_DIMNAME (NCID, DIMID, name)
INTEGER FUNCTION NF_INQ_DIMLEN (NCID, DIMID, len)
INTEGER FUNCTION NF_RENAME_DIM (NCID, DIMID, NAME)
INTEGER FUNCTION NF_DEF_VAR (NCID, NAME, XTYPE, NDIMS, DIMIDS,
varid)
INTEGER FUNCTION NF_INQ_VAR (NCID, VARID, name, xtype, ndims,
dimids, natts)
INTEGER FUNCTION NF_INQ_VARID (NCID, NAME, varid)
INTEGER FUNCTION NF_INQ_VARNAME (NCID, VARID, name)
INTEGER FUNCTION NF_INQ_VARTYPE (NCID, VARID, xtype)
INTEGER FUNCTION NF_INQ_VARNDIMS (NCID, VARID, ndims)
INTEGER FUNCTION NF_INQ_VARDIMID (NCID, VARID, DIMIDS)
INTEGER FUNCTION NF_INQ_VARNATTS (NCID, VARID, natts)
INTEGER FUNCTION NF_RENAME_VAR (NCID, VARID, NAME)
INTEGER FUNCTION NF_PUT_VAR_TEXT (NCID, VARID, TEXT)
INTEGER FUNCTION NF_GET_VAR_TEXT (NCID, VARID, text)
INTEGER FUNCTION NF_PUT_VAR_INT1 (NCID, VARID, I1VAL)
INTEGER FUNCTION NF_GET_VAR_INT1 (NCID, VARID, i1val)
INTEGER FUNCTION NF_PUT_VAR_INT2 (NCID, VARID, I2VAL)
INTEGER FUNCTION NF_GET_VAR_INT2 (NCID, VARID, i2val)
INTEGER FUNCTION NF_PUT_VAR_INT (NCID, VARID, IVAL)
INTEGER FUNCTION NF_GET_VAR_INT (NCID, VARID, ival)
INTEGER FUNCTION NF_PUT_VAR_REAL (NCID, VARID, RVAL)
INTEGER FUNCTION NF_GET_VAR_REAL (NCID, VARID, rval)
INTEGER FUNCTION NF_PUT_VAR_DOUBLE (NCID, VARID, DVAL)
INTEGER FUNCTION NF_GET_VAR_DOUBLE (NCID, VARID, dval)
INTEGER FUNCTION NF_PUT_VAR1_TEXT (NCID, VARID, INDEX, TEXT)
INTEGER FUNCTION NF_GET_VAR1_TEXT (NCID, VARID, INDEX, text)
INTEGER FUNCTION NF_PUT_VAR1_INT1 (NCID, VARID, INDEX, I1VAL)
INTEGER FUNCTION NF_GET_VAR1_INT1 (NCID, VARID, INDEX, i1val)
INTEGER FUNCTION NF_PUT_VAR1_INT2 (NCID, VARID, INDEX, I2VAL)
INTEGER FUNCTION NF_GET_VAR1_INT2 (NCID, VARID, INDEX, i2val)
INTEGER FUNCTION NF_PUT_VAR1_INT (NCID, VARID, INDEX, IVAL)
INTEGER FUNCTION NF_GET_VAR1_INT (NCID, VARID, INDEX, ival)
INTEGER FUNCTION NF_PUT_VAR1_REAL (NCID, VARID, INDEX, RVAL)
INTEGER FUNCTION NF_GET_VAR1_REAL (NCID, VARID, INDEX, rval)
INTEGER FUNCTION NF_PUT_VAR1_DOUBLE(NCID, VARID, INDEX, DVAL)
INTEGER FUNCTION NF_GET_VAR1_DOUBLE(NCID, VARID, INDEX, dval)
INTEGER FUNCTION NF_PUT_VARA_TEXT (NCID, VARID, START, COUNT, TEXT)
INTEGER FUNCTION NF_GET_VARA_TEXT (NCID, VARID, START, COUNT, text)
INTEGER FUNCTION NF_PUT_VARA_INT1 (NCID, VARID, START, COUNT, I1VALS)
INTEGER FUNCTION NF_GET_VARA_INT1 (NCID, VARID, START, COUNT, i1vals)
INTEGER FUNCTION NF_PUT_VARA_INT2 (NCID, VARID, START, COUNT, I2VALS)
INTEGER FUNCTION NF_GET_VARA_INT2 (NCID, VARID, START, COUNT, i2vals)
INTEGER FUNCTION NF_PUT_VARA_INT (NCID, VARID, START, COUNT, IVALS)
INTEGER FUNCTION NF_GET_VARA_INT (NCID, VARID, START, COUNT, ivals)
INTEGER FUNCTION NF_PUT_VARA_REAL (NCID, VARID, START, COUNT, RVALS)
INTEGER FUNCTION NF_GET_VARA_REAL (NCID, VARID, START, COUNT, rvals)
INTEGER FUNCTION NF_PUT_VARA_DOUBLE(NCID, VARID, START, COUNT, DVALS)
INTEGER FUNCTION NF_GET_VARA_DOUBLE(NCID, VARID, START, COUNT, dvals)
INTEGER FUNCTION NF_PUT_VARS_TEXT (NCID, VARID, START, COUNT, STRIDE,
TEXT)
INTEGER FUNCTION NF_GET_VARS_TEXT (NCID, VARID, START, COUNT, STRIDE,
text)
INTEGER FUNCTION NF_PUT_VARS_INT1 (NCID, VARID, START, COUNT, STRIDE,
I1VALS)
INTEGER FUNCTION NF_GET_VARS_INT1 (NCID, VARID, START, COUNT, STRIDE,
i1vals)
INTEGER FUNCTION NF_PUT_VARS_INT2 (NCID, VARID, START, COUNT, STRIDE,
I2VALS)
INTEGER FUNCTION NF_GET_VARS_INT2 (NCID, VARID, START, COUNT, STRIDE,
i2vals)
INTEGER FUNCTION NF_PUT_VARS_INT (NCID, VARID, START, COUNT, STRIDE,
IVALS)
INTEGER FUNCTION NF_GET_VARS_INT (NCID, VARID, START, COUNT, STRIDE,
ivals)
INTEGER FUNCTION NF_PUT_VARS_REAL (NCID, VARID, START, COUNT, STRIDE,
RVALS)
INTEGER FUNCTION NF_GET_VARS_REAL (NCID, VARID, START, COUNT, STRIDE,
rvals)
INTEGER FUNCTION NF_PUT_VARS_DOUBLE(NCID, VARID, START, COUNT, STRIDE,
DVALS)
INTEGER FUNCTION NF_GET_VARS_DOUBLE(NCID, VARID, START, COUNT, STRIDE,
dvals)
INTEGER FUNCTION NF_PUT_VARM_TEXT (NCID, VARID, START, COUNT, STRIDE,
IMAP, TEXT)
INTEGER FUNCTION NF_GET_VARM_TEXT (NCID, VARID, START, COUNT, STRIDE,
IMAP, text)
INTEGER FUNCTION NF_PUT_VARM_INT1 (NCID, VARID, START, COUNT, STRIDE,
IMAP, I1VALS)
INTEGER FUNCTION NF_GET_VARM_INT1 (NCID, VARID, START, COUNT, STRIDE,
IMAP, i1vals)
INTEGER FUNCTION NF_PUT_VARM_INT2 (NCID, VARID, START, COUNT, STRIDE,
IMAP, I2VALS)
INTEGER FUNCTION NF_GET_VARM_INT2 (NCID, VARID, START, COUNT, STRIDE,
IMAP, i2vals)
INTEGER FUNCTION NF_PUT_VARM_INT (NCID, VARID, START, COUNT, STRIDE,
IMAP, IVALS)
INTEGER FUNCTION NF_GET_VARM_INT (NCID, VARID, START, COUNT, STRIDE,
IMAP, ivals)
INTEGER FUNCTION NF_PUT_VARM_REAL (NCID, VARID, START, COUNT, STRIDE,
IMAP, RVALS)
INTEGER FUNCTION NF_GET_VARM_REAL (NCID, VARID, START, COUNT, STRIDE,
IMAP, rvals)
INTEGER FUNCTION NF_PUT_VARM_DOUBLE(NCID, VARID, START, COUNT, STRIDE,
IMAP, DVALS)
INTEGER FUNCTION NF_GET_VARM_DOUBLE(NCID, VARID, START, COUNT, STRIDE,
IMAP, dvals)
INTEGER FUNCTION NF_INQ_ATT (NCID, VARID, NAME, xtype, len)
INTEGER FUNCTION NF_INQ_ATTID (NCID, VARID, NAME, attnum)
INTEGER FUNCTION NF_INQ_ATTTYPE (NCID, VARID, NAME, xtype)
INTEGER FUNCTION NF_INQ_ATTLEN (NCID, VARID, NAME, len)
INTEGER FUNCTION NF_INQ_ATTNAME (NCID, VARID, ATTNUM, name)
INTEGER FUNCTION NF_COPY_ATT (NCID_IN, VARID_IN, NAME,
NCID_OUT, VARID_OUT)
INTEGER FUNCTION NF_RENAME_ATT (NCID, VARID, CURNAME, NEWNAME)
INTEGER FUNCTION NF_DEL_ATT (NCID, VARID, NAME)
INTEGER FUNCTION NF_PUT_ATT_TEXT (NCID, VARID, NAME, LEN, TEXT)
INTEGER FUNCTION NF_GET_ATT_TEXT (NCID, VARID, NAME, text)
INTEGER FUNCTION NF_PUT_ATT_INT1 (NCID, VARID, NAME, XTYPE, LEN,
I1VALS)
INTEGER FUNCTION NF_GET_ATT_INT1 (NCID, VARID, NAME, i1vals)
INTEGER FUNCTION NF_PUT_ATT_INT2 (NCID, VARID, NAME, XTYPE, LEN,
I2VALS)
INTEGER FUNCTION NF_GET_ATT_INT2 (NCID, VARID, NAME, i2vals)
INTEGER FUNCTION NF_PUT_ATT_INT (NCID, VARID, NAME, XTYPE, LEN,
IVALS)
INTEGER FUNCTION NF_GET_ATT_INT (NCID, VARID, NAME, ivals)
INTEGER FUNCTION NF_PUT_ATT_REAL (NCID, VARID, NAME, XTYPE, LEN,
RVALS)
INTEGER FUNCTION NF_GET_ATT_REAL (NCID, VARID, NAME, rvals)
INTEGER FUNCTION NF_PUT_ATT_DOUBLE (NCID, VARID, NAME, XTYPE, LEN,
DVALS)
INTEGER FUNCTION NF_GET_ATT_DOUBLE (NCID, VARID, NAME, dvals)
INTEGER ATTNUM ! attribute number
INTEGER attnum ! returned attribute number
INTEGER CMODE ! NF_NOCLOBBER, NF_SHARE flags expression
INTEGER COUNT ! array of edge lengths of block of values
CHARACTER(*) CURNAME ! current name (before renaming)
INTEGER DIMID ! dimension ID
INTEGER dimid ! returned dimension ID
INTEGER DIMIDS ! list of dimension IDs
INTEGER dimids ! list of returned dimension IDs
DOUBLEPRECISION DVAL ! single data value
DOUBLEPRECISION dval ! returned single data value
DOUBLEPRECISION DVALS ! array of data values
DOUBLEPRECISION dvals ! array of returned data values
INTEGER FILLMODE ! NF_NOFILL or NF_FILL, for setting fill mode
INTEGER*1 I1VAL ! single data value
INTEGER*1 I1val ! returned single data value
INTEGER*1 I1VALS ! array of data values
INTEGER*1 i1vals ! array of returned data values
INTEGER*2 I2VAL ! single data value
INTEGER*2 i2val ! returned single data value
INTEGER*2 I2VALS ! array of data values
INTEGER*2 i2vals ! array of returned data values
INTEGER IMAP ! index mapping vector
INTEGER INDEX ! variable array index vector
INTEGER IVAL ! single data value
INTEGER ival ! returned single data value
INTEGER IVALS ! array of data values
INTEGER ivals ! array of returned data values
INTEGER LEN ! dimension or attribute length
INTEGER len ! returned dimension or attribute length
INTEGER MODE ! open mode, one of NF_WRITE or NF_NOWRITE
CHARACTER(*) NAME ! dimension, variable, or attribute name
CHARACTER(*) name ! returned dim, var, or att name
INTEGER natts ! returned number of attributes
INTEGER NCERR ! error returned from NF_xxx function call
INTEGER NCID ! netCDF ID of an open netCDF dataset
INTEGER ncid ! returned netCDF ID
INTEGER NCID_IN ! netCDF ID of open source netCDF dataset
INTEGER NCID_OUT ! netCDF ID of open destination netCDF dataset
INTEGER NDIMS ! number of dimensions
INTEGER ndims ! returned number of dimensions
CHARACTER(*) NEWNAME ! new name for dim, var, or att
INTEGER ngatts ! returned number of global attributes
INTEGER nvars ! returned number of variables
INTEGER old_mode ! previous fill mode, NF_NOFILL or NF_FILL,
CHARACTER(*) PATH ! name of netCDF dataset
REAL RVAL ! single data value
REAL rval ! returned single data value
REAL RVALS ! array of data values
REAL rvals ! array of returned data values
INTEGER START ! variable array indices of first value
INTEGER STRIDE ! variable array dimensional strides
CHARACTER(*) TEXT ! input text value
CHARACTER(*) text ! returned text value
INTEGER unlimdimid ! returned ID of unlimited dimension
INTEGER VARID ! variable ID
INTEGER varid ! returned variable ID
INTEGER VARID_IN ! variable ID
INTEGER VARID_OUT ! variable ID
INTEGER XTYPE ! external type: NF_BYTE, NF_CHAR, ... ,
INTEGER xtype ! returned external type
~~~~

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