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# Tables

## `BinTableHDU`

class `astropy.io.fits.``BinTableHDU`(data=None, header=None, name=None, uint=False)

  Bases: `astropy.io.fits.hdu.table._TableBaseHDU`

  Binary table HDU class.

  `add_checksum`(when=None, override_datasum=False, blocking='standard', checksum_keyword='CHECKSUM', datasum_keyword='DATASUM')

    Add the `CHECKSUM` and `DATASUM` cards to this HDU with the values set to the checksum calculated for the HDU and the data respectively. The addition of the `DATASUM` card may be overridden.

    Parameters:

    when : str, optional

    > comment string for the cards; by default the comments will represent the time when the checksum was calculated

    override_datasum : bool, optional

    > add the `CHECKSUM` card only

    blocking : str, optional

    > “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    checksum_keyword: str, optional :

    > The name of the header keyword to store the checksum value in; this is typically ‘CHECKSUM’ per convention, but there exist use cases in which a different keyword should be used

    datasum_keyword: str, optional :

    > See `checksum_keyword`

    Notes

    For testing purposes, first call `add_datasum` with a `when` argument, then call `add_checksum` with a `when` argument and `override_datasum` set to `True`. This will provide consistent comments for both cards and enable the generation of a `CHECKSUM` card with a consistent value.

  `add_datasum`(when=None, blocking='standard', datasum_keyword='DATASUM')

    Add the `DATASUM` card to this HDU with the value set to the checksum calculated for the data.

    Parameters:

    when : str, optional

    > Comment string for the card that by default represents the time when the checksum was calculated

    blocking : str, optional

    > “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    datasum_keyword: str, optional :

    > The name of the header keyword to store the datasum value in; this is typically ‘DATASUM’ per convention, but there exist use cases in which a different keyword should be used

    Returns:

    checksum : int

    > The calculated datasum

    Notes

    For testing purposes, provide a `when` argument to enable the comment value in the card to remain consistent. This will enable the generation of a `CHECKSUM` card with a consistent value.

  `copy`()

    Make a copy of the table HDU, both header and data are copied.

  `dump`(datafile=None, cdfile=None, hfile=None, clobber=False)

    Dump the table HDU to a file in ASCII format. The table may be dumped in three separate files, one containing column definitions, one containing header parameters, and one for table data.

    Parameters:

    datafile : file path, file object or file-like object, optional

    > Output data file. The default is the root name of the fits file associated with this HDU appended with the extension `.txt`.

    cdfile : file path, file object or file-like object, optional

    > Output column definitions file. The default is `None`, no column definitions output is produced.

    hfile : file path, file object or file-like object, optional

    > Output header parameters file. The default is `None`, no header parameters output is produced.

    clobber : bool

    > Overwrite the output files if they exist.

    Notes

    The primary use for the `dump` method is to allow viewing and editing the table data and parameters in a standard text editor. The `load` method can be used to create a new table from the three plain text (ASCII) files.

    - datafile: Each line of the data file represents one row of table data. The data is output one column at a time in column order. If a column contains an array, each element of the column array in the current row is output before moving on to the next column. Each row ends with a new line.

      Integer data is output right-justified in a 21-character field followed by a blank. Floating point data is output right justified using ‘g’ format in a 21-character field with 15 digits of precision, followed by a blank. String data that does not contain whitespace is output left-justified in a field whose width matches the width specified in the `TFORM` header parameter for the column, followed by a blank. When the string data contains whitespace characters, the string is enclosed in quotation marks (`""`). For the last data element in a row, the trailing blank in the field is replaced by a new line character.

      For column data containing variable length arrays (‘P’ format), the array data is preceded by the string `'VLA_Length= '` and the integer length of the array for that row, left-justified in a 21-character field, followed by a blank.

      Note

      This format does not support variable length arrays using the (‘Q’ format) due difficult to overcome ambiguities. What this means is that this file format cannot support VLA columns in tables stored in files that are over 2 GB in size.

      For column data representing a bit field (‘X’ format), each bit value in the field is output right-justified in a 21-character field as 1 (for true) or 0 (for false).

    - cdfile: Each line of the column definitions file provides the definitions for one column in the table. The line is broken up into 8, sixteen-character fields. The first field provides the column name (`TTYPEn`). The second field provides the column format (`TFORMn`). The third field provides the display format (`TDISPn`). The fourth field provides the physical units (`TUNITn`). The fifth field provides the dimensions for a multidimensional array (`TDIMn`). The sixth field provides the value that signifies an undefined value (`TNULLn`). The seventh field provides the scale factor (`TSCALn`). The eighth field provides the offset value (`TZEROn`). A field value of `""` is used to represent the case where no value is provided.

    - hfile: Each line of the header parameters file provides the definition of a single HDU header card as represented by the card image.

  `filebytes`()

    Calculates and returns the number of bytes that this HDU will write to a file.

    Parameters: | None :
    Returns: | Number of bytes :

  `fileinfo`()

    Returns a dictionary detailing information about the locations of this HDU within any associated file. The values are only valid after a read or write of the associated file with no intervening changes to the `HDUList`.

    Parameters: | None :

    Returns:

    dictionary or None :

    > The dictionary details information about the locations of this HDU within an associated file. Returns `None` when the HDU is not associated with a file.

    > Dictionary contents:

    > Key | Value
    > --- | ---
    > file | File object associated with the HDU
    > filemode | Mode in which the file was opened (readonly, copyonwrite, update, append, ostream)
    > hdrLoc | Starting byte location of header in file
    > datLoc | Starting byte location of data block in file
    > datSpan | Data size including padding

  classmethod `fromstring`(data, fileobj=None, offset=0, checksum=False, ignore_missing_end=False, **kwargs)

    Creates a new HDU object of the appropriate type from a string containing the HDU’s entire header and, optionally, its data.

    Note: When creating a new HDU from a string without a backing file object, the data of that HDU may be read-only. It depends on whether the underlying string was an immutable Python str/bytes object, or some kind of read-write memory buffer such as a `memoryview`.

    Parameters:

    data : str, bytearray, memoryview, ndarray

    > A byte string contining the HDU’s header and, optionally, its data. If `fileobj` is not specified, and the length of `data` extends beyond the header, then the trailing data is taken to be the HDU’s data. If `fileobj` is specified then the trailing data is ignored.

    fileobj : file (optional)

    > The file-like object that this HDU was read from.

    offset : int (optional)

    > If `fileobj` is specified, the offset into the file-like object at which this HDU begins.

    checksum : bool (optional)

    > Check the HDU’s checksum and/or datasum.

    ignore_missing_end : bool (optional)

    > Ignore a missing end card in the header data. Note that without the end card the end of the header can’t be found, so the entire data is just assumed to be the header.

    kwargs : (optional)

    > May contain additional keyword arguments specific to an HDU type. Any unrecognized kwargs are simply ignored.

  classmethod `load`(datafile, cdfile=None, hfile=None, replace=False, header=None)

    Create a table from the input ASCII files. The input is from up to three separate files, one containing column definitions, one containing header parameters, and one containing column data.

    The column definition and header parameters files are not required. When absent the column definitions and/or header parameters are taken from the header object given in the header argument; otherwise sensible defaults are inferred (though this mode is not recommended).

    Parameters:

    datafile : file path, file object or file-like object

    > Input data file containing the table data in ASCII format.

    cdfile : file path, file object, file-like object, optional

    > Input column definition file containing the names, formats, display formats, physical units, multidimensional array dimensions, undefined values, scale factors, and offsets associated with the columns in the table. If `None`, the column definitions are taken from the current values in this object.

    hfile : file path, file object, file-like object, optional

    > Input parameter definition file containing the header parameter definitions to be associated with the table. If `None`, the header parameter definitions are taken from the current values in this objects header.

    replace : bool

    > When `True`, indicates that the entire header should be replaced with the contents of the ASCII file instead of just updating the current header.

    header : Header object

    > When the cdfile and hfile are missing, use this Header object in the creation of the new table and HDU. Otherwise this Header supercedes the keywords from hfile, which is only used to update values not present in this Header, unless replace=True in which this Header’s values are completely replaced with the values from hfile.

    Notes

    The primary use for the `load` method is to allow the input of ASCII data that was edited in a standard text editor of the table data and parameters. The `dump` method can be used to create the initial ASCII files.

    - datafile: Each line of the data file represents one row of table data. The data is output one column at a time in column order. If a column contains an array, each element of the column array in the current row is output before moving on to the next column. Each row ends with a new line.

      Integer data is output right-justified in a 21-character field followed by a blank. Floating point data is output right justified using ‘g’ format in a 21-character field with 15 digits of precision, followed by a blank. String data that does not contain whitespace is output left-justified in a field whose width matches the width specified in the `TFORM` header parameter for the column, followed by a blank. When the string data contains whitespace characters, the string is enclosed in quotation marks (`""`). For the last data element in a row, the trailing blank in the field is replaced by a new line character.

      For column data containing variable length arrays (‘P’ format), the array data is preceded by the string `'VLA_Length= '` and the integer length of the array for that row, left-justified in a 21-character field, followed by a blank.

      Note

      This format does not support variable length arrays using the (‘Q’ format) due difficult to overcome ambiguities. What this means is that this file format cannot support VLA columns in tables stored in files that are over 2 GB in size.

      For column data representing a bit field (‘X’ format), each bit value in the field is output right-justified in a 21-character field as 1 (for true) or 0 (for false).

    - cdfile: Each line of the column definitions file provides the definitions for one column in the table. The line is broken up into 8, sixteen-character fields. The first field provides the column name (`TTYPEn`). The second field provides the column format (`TFORMn`). The third field provides the display format (`TDISPn`). The fourth field provides the physical units (`TUNITn`). The fifth field provides the dimensions for a multidimensional array (`TDIMn`). The sixth field provides the value that signifies an undefined value (`TNULLn`). The seventh field provides the scale factor (`TSCALn`). The eighth field provides the offset value (`TZEROn`). A field value of `""` is used to represent the case where no value is provided.

    - hfile: Each line of the header parameters file provides the definition of a single HDU header card as represented by the card image.

  classmethod `readfrom`(fileobj, checksum=False, ignore_missing_end=False, **kwargs)

    Read the HDU from a file. Normally an HDU should be opened with `fitsopen()` which reads the entire HDU list in a FITS file. But this method is still provided for symmetry with `writeto()`.

    Parameters:

    fileobj : file object or file-like object

    > Input FITS file. The file’s seek pointer is assumed to be at the beginning of the HDU.

    checksum : bool

    > If `True`, verifies that both `DATASUM` and `CHECKSUM` card values (when present in the HDU header) match the header and data of all HDU’s in the file.

    ignore_missing_end : bool

    > Do not issue an exception when opening a file that is missing an `END` card in the last header.

  `req_cards`(keyword, pos, test, fix_value, option, errlist)

    Check the existence, location, and value of a required `Card`.

    TODO: Write about parameters

    If `pos` = `None`, it can be anywhere. If the card does not exist, the new card will have the `fix_value` as its value when created. Also check the card’s value by using the `test` argument.

  `run_option`(option='warn', err_text='', fix_text='Fixed.', fix=None, fixable=True)

    Execute the verification with selected option.

  `size`

    Size (in bytes) of the data portion of the HDU.

  classmethod `tcreate`(*args, **kwargs)

    Deprecated since version 3.1: Use `load()` instead.

  `tdump`(*args, **kwargs)

    Deprecated since version 3.1: Use `dump()` instead.

  `update`()

    Update header keywords to reflect recent changes of columns.

  `update_ext_name`(*args, **kwargs)

    Deprecated since version 3.2: Use the `.name` attribute or `Header.set` instead.

    Update the extension name associated with the HDU.

    If the keyword already exists in the Header, it’s value and/or comment will be updated. If it does not exist, a new card will be created and it will be placed before or after the specified location. If no `before` or `after` is specified, it will be appended at the end.

    Parameters:

    value : str

    > value to be used for the new extension name

    comment : str, optional

    > to be used for updating, default=None.

    before : str or int, optional

    > name of the keyword, or index of the `Card` before which the new card will be placed in the Header. The argument `before` takes precedence over `after` if both specified.

    after : str or int, optional

    > name of the keyword, or index of the `Card` after which the new card will be placed in the Header.

    savecomment : bool, optional

    > When `True`, preserve the current comment for an existing keyword. The argument `savecomment` takes precedence over `comment` if both specified. If `comment` is not specified then the current comment will automatically be preserved.

  `update_ext_version`(*args, **kwargs)

    Deprecated since version 3.2: Use the `ver` attribute or `Header.set` instead.

    Update the extension version associated with the HDU.

    If the keyword already exists in the Header, it’s value and/or comment will be updated. If it does not exist, a new card will be created and it will be placed before or after the specified location. If no `before` or `after` is specified, it will be appended at the end.

    Parameters:

    value : str

    > value to be used for the new extension version

    comment : str, optional

    > to be used for updating, default=None.

    before : str or int, optional

    > name of the keyword, or index of the `Card` before which the new card will be placed in the Header. The argument `before` takes precedence over `after` if both specified.

    after : str or int, optional

    > name of the keyword, or index of the `Card` after which the new card will be placed in the Header.

    savecomment : bool, optional

    > When `True`, preserve the current comment for an existing keyword. The argument `savecomment` takes precedence over `comment` if both specified. If `comment` is not specified then the current comment will automatically be preserved.

  `verify`(option='warn')

    Verify all values in the instance.

    Parameters:

    option : str

    > Output verification option. Must be one of `"fix"`, `"silentfix"`, `"ignore"`, `"warn"`, or `"exception"`. See Verification options for more info.

  `verify_checksum`(blocking='standard')

    Verify that the value in the `CHECKSUM` keyword matches the value calculated for the current HDU CHECKSUM.

    blocking: str, optional
      “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    Returns:

    valid : int

    > - 0 - failure
    > - 1 - success
    > - 2 - no `CHECKSUM` keyword present

  `verify_datasum`(blocking='standard')

    Verify that the value in the `DATASUM` keyword matches the value calculated for the `DATASUM` of the current HDU data.

    blocking: str, optional
      “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    Returns:

    valid : int

    > - 0 - failure
    > - 1 - success
    > - 2 - no `DATASUM` keyword present

  `writeto`(name, output_verify='exception', clobber=False, checksum=False)

    Works similarly to the normal writeto(), but prepends a default `PrimaryHDU` are required by extension HDUs (which cannot stand on their own).

## `TableHDU`

class `astropy.io.fits.``TableHDU`(data=None, header=None, name=None)

  Bases: `astropy.io.fits.hdu.table._TableBaseHDU`

  FITS ASCII table extension HDU class.

  `add_checksum`(when=None, override_datasum=False, blocking='standard', checksum_keyword='CHECKSUM', datasum_keyword='DATASUM')

    Add the `CHECKSUM` and `DATASUM` cards to this HDU with the values set to the checksum calculated for the HDU and the data respectively. The addition of the `DATASUM` card may be overridden.

    Parameters:

    when : str, optional

    > comment string for the cards; by default the comments will represent the time when the checksum was calculated

    override_datasum : bool, optional

    > add the `CHECKSUM` card only

    blocking : str, optional

    > “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    checksum_keyword: str, optional :

    > The name of the header keyword to store the checksum value in; this is typically ‘CHECKSUM’ per convention, but there exist use cases in which a different keyword should be used

    datasum_keyword: str, optional :

    > See `checksum_keyword`

    Notes

    For testing purposes, first call `add_datasum` with a `when` argument, then call `add_checksum` with a `when` argument and `override_datasum` set to `True`. This will provide consistent comments for both cards and enable the generation of a `CHECKSUM` card with a consistent value.

  `add_datasum`(when=None, blocking='standard', datasum_keyword='DATASUM')

    Add the `DATASUM` card to this HDU with the value set to the checksum calculated for the data.

    Parameters:

    when : str, optional

    > Comment string for the card that by default represents the time when the checksum was calculated

    blocking : str, optional

    > “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    datasum_keyword: str, optional :

    > The name of the header keyword to store the datasum value in; this is typically ‘DATASUM’ per convention, but there exist use cases in which a different keyword should be used

    Returns:

    checksum : int

    > The calculated datasum

    Notes

    For testing purposes, provide a `when` argument to enable the comment value in the card to remain consistent. This will enable the generation of a `CHECKSUM` card with a consistent value.

  `copy`()

    Make a copy of the table HDU, both header and data are copied.

  `filebytes`()

    Calculates and returns the number of bytes that this HDU will write to a file.

    Parameters: | None :
    Returns: | Number of bytes :

  `fileinfo`()

    Returns a dictionary detailing information about the locations of this HDU within any associated file. The values are only valid after a read or write of the associated file with no intervening changes to the `HDUList`.

    Parameters: | None :

    Returns:

    dictionary or None :

    > The dictionary details information about the locations of this HDU within an associated file. Returns `None` when the HDU is not associated with a file.

    > Dictionary contents:

    > Key | Value
    > --- | ---
    > file | File object associated with the HDU
    > filemode | Mode in which the file was opened (readonly, copyonwrite, update, append, ostream)
    > hdrLoc | Starting byte location of header in file
    > datLoc | Starting byte location of data block in file
    > datSpan | Data size including padding

  classmethod `fromstring`(data, fileobj=None, offset=0, checksum=False, ignore_missing_end=False, **kwargs)

    Creates a new HDU object of the appropriate type from a string containing the HDU’s entire header and, optionally, its data.

    Note: When creating a new HDU from a string without a backing file object, the data of that HDU may be read-only. It depends on whether the underlying string was an immutable Python str/bytes object, or some kind of read-write memory buffer such as a `memoryview`.

    Parameters:

    data : str, bytearray, memoryview, ndarray

    > A byte string contining the HDU’s header and, optionally, its data. If `fileobj` is not specified, and the length of `data` extends beyond the header, then the trailing data is taken to be the HDU’s data. If `fileobj` is specified then the trailing data is ignored.

    fileobj : file (optional)

    > The file-like object that this HDU was read from.

    offset : int (optional)

    > If `fileobj` is specified, the offset into the file-like object at which this HDU begins.

    checksum : bool (optional)

    > Check the HDU’s checksum and/or datasum.

    ignore_missing_end : bool (optional)

    > Ignore a missing end card in the header data. Note that without the end card the end of the header can’t be found, so the entire data is just assumed to be the header.

    kwargs : (optional)

    > May contain additional keyword arguments specific to an HDU type. Any unrecognized kwargs are simply ignored.

  classmethod `readfrom`(fileobj, checksum=False, ignore_missing_end=False, **kwargs)

    Read the HDU from a file. Normally an HDU should be opened with `fitsopen()` which reads the entire HDU list in a FITS file. But this method is still provided for symmetry with `writeto()`.

    Parameters:

    fileobj : file object or file-like object

    > Input FITS file. The file’s seek pointer is assumed to be at the beginning of the HDU.

    checksum : bool

    > If `True`, verifies that both `DATASUM` and `CHECKSUM` card values (when present in the HDU header) match the header and data of all HDU’s in the file.

    ignore_missing_end : bool

    > Do not issue an exception when opening a file that is missing an `END` card in the last header.

  `req_cards`(keyword, pos, test, fix_value, option, errlist)

    Check the existence, location, and value of a required `Card`.

    TODO: Write about parameters

    If `pos` = `None`, it can be anywhere. If the card does not exist, the new card will have the `fix_value` as its value when created. Also check the card’s value by using the `test` argument.

  `run_option`(option='warn', err_text='', fix_text='Fixed.', fix=None, fixable=True)

    Execute the verification with selected option.

  `size`

    Size (in bytes) of the data portion of the HDU.

  `update`()

    Update header keywords to reflect recent changes of columns.

  `update_ext_name`(*args, **kwargs)

    Deprecated since version 3.2: Use the `.name` attribute or `Header.set` instead.

    Update the extension name associated with the HDU.

    If the keyword already exists in the Header, it’s value and/or comment will be updated. If it does not exist, a new card will be created and it will be placed before or after the specified location. If no `before` or `after` is specified, it will be appended at the end.

    Parameters:

    value : str

    > value to be used for the new extension name

    comment : str, optional

    > to be used for updating, default=None.

    before : str or int, optional

    > name of the keyword, or index of the `Card` before which the new card will be placed in the Header. The argument `before` takes precedence over `after` if both specified.

    after : str or int, optional

    > name of the keyword, or index of the `Card` after which the new card will be placed in the Header.

    savecomment : bool, optional

    > When `True`, preserve the current comment for an existing keyword. The argument `savecomment` takes precedence over `comment` if both specified. If `comment` is not specified then the current comment will automatically be preserved.

  `update_ext_version`(*args, **kwargs)

    Deprecated since version 3.2: Use the `ver` attribute or `Header.set` instead.

    Update the extension version associated with the HDU.

    If the keyword already exists in the Header, it’s value and/or comment will be updated. If it does not exist, a new card will be created and it will be placed before or after the specified location. If no `before` or `after` is specified, it will be appended at the end.

    Parameters:

    value : str

    > value to be used for the new extension version

    comment : str, optional

    > to be used for updating, default=None.

    before : str or int, optional

    > name of the keyword, or index of the `Card` before which the new card will be placed in the Header. The argument `before` takes precedence over `after` if both specified.

    after : str or int, optional

    > name of the keyword, or index of the `Card` after which the new card will be placed in the Header.

    savecomment : bool, optional

    > When `True`, preserve the current comment for an existing keyword. The argument `savecomment` takes precedence over `comment` if both specified. If `comment` is not specified then the current comment will automatically be preserved.

  `verify`(option='warn')

    Verify all values in the instance.

    Parameters:

    option : str

    > Output verification option. Must be one of `"fix"`, `"silentfix"`, `"ignore"`, `"warn"`, or `"exception"`. See Verification options for more info.

  `verify_checksum`(blocking='standard')

    Verify that the value in the `CHECKSUM` keyword matches the value calculated for the current HDU CHECKSUM.

    blocking: str, optional
      “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    Returns:

    valid : int

    > - 0 - failure
    > - 1 - success
    > - 2 - no `CHECKSUM` keyword present

  `verify_datasum`(blocking='standard')

    Verify that the value in the `DATASUM` keyword matches the value calculated for the `DATASUM` of the current HDU data.

    blocking: str, optional
      “standard” or “nonstandard”, compute sum 2880 bytes at a time, or not

    Returns:

    valid : int

    > - 0 - failure
    > - 1 - success
    > - 2 - no `DATASUM` keyword present

  `writeto`(name, output_verify='exception', clobber=False, checksum=False)

    Works similarly to the normal writeto(), but prepends a default `PrimaryHDU` are required by extension HDUs (which cannot stand on their own).

## `Column`

class `astropy.io.fits.``Column`(name=None, format=None, unit=None, null=None, bscale=None, bzero=None, disp=None, start=None, dim=None, array=None, ascii=None)

  Bases: `object`

  Class which contains the definition of one column, e.g. `ttype`, `tform`, etc. and the array containing values for the column. Does not support `theap` yet.

  `copy`()

    Return a copy of this `Column`.

## `ColDefs`

class `astropy.io.fits.``ColDefs`(input, tbtype='BinTableHDU')

  Bases: `object`

  Column definitions class.

  It has attributes corresponding to the `Column` attributes (e.g. `ColDefs` has the attribute `names` while `Column` has `name`). Each attribute in `ColDefs` is a list of corresponding attribute values from all `Column` objects.

  `add_col`(column)

    Append one `Column` to the column definition.

  `change_attrib`(col_name, attrib, new_value)

    Change an attribute (in the commonName list) of a `Column`.

    col_name : str or int
      The column name or index to change
    attrib : str
      The attribute name
    value : object
      The new value for the attribute
  `change_name`(col_name, new_name)

    Change a `Column`‘s name.

    col_name : str
      The current name of the column
    new_name : str
      The new name of the column
  `change_unit`(col_name, new_unit)

    Change a `Column`‘s unit.

    col_name : str or int
      The column name or index
    new_unit : str
      The new unit for the column
  `del_col`(col_name)

    Delete (the definition of) one `Column`.

    col_name : str or int
      The column’s name or index
  `info`(attrib='all', output=None)

    Get attribute(s) information of the column definition.

    Parameters:

    attrib : str

    > Can be one or more of the attributes listed in `KEYWORD_ATTRIBUTES`. The default is `"all"` which will print out all attributes. It forgives plurals and blanks. If there are two or more attribute names, they must be separated by comma(s).

    output : file, optional

    > File-like object to output to. Outputs to stdout by default. If False, returns the attributes as a dict instead.

    Notes

    This function doesn’t return anything by default; it just prints to stdout.

## `FITS_rec`

class `astropy.io.fits.``FITS_rec`

  Bases: `numpy.core.records.recarray`

  FITS record array class.

  `FITS_rec` is the data part of a table HDU’s data part. This is a layer over the `recarray`, so we can deal with scaled columns.

  It inherits all of the standard methods from `numpy.ndarray`.

  `columns`

    A user-visible accessor for the coldefs. See ticket #44.

  `copy`(order='C')

    The Numpy documentation lies; ndarray.copy is not equivalent to np.copy. Differences include that it re-views the copied array as self’s ndarray subclass, as though it were taking a slice; this means __array_finalize__ is called and the copy shares all the array attributes (including ._convert!). So we need to make a deep copy of all those attributes so that the two arrays truly do not share any data.

    Note: The `order` argument is unsupported in Numpy 1.5 and will be ignored when used with that version.

  `field`(key)

    A view of a `Column`‘s data as an array.

  classmethod `from_columns`(columns, nrows=0, fill=False)

    Given a ColDefs object of unknown origin, initialize a new FITS_rec object.

    This was originally part of the new_table function in the table module but was moved into a class method since most of its functionality always had more to do with initializing a FITS_rec object than anything else, and much of it also overlapped with FITS_rec._scale_back.

    Parameters:

    columns : sequence of Columns or a ColDefs

    > The columns from which to create the table data. If these columns have data arrays attached that data may be used in initializing the new table. Otherwise the input columns will be used as a template for a new table with the requested number of rows.

    nrows : int

    > Number of rows in the new table. If the input columns have data associated with them, the size of the largest input column is used. Otherwise the default is 0.

    fill : bool

    > If `True`, will fill all cells with zeros or blanks. If `False`, copy the data from input, undefined cells will still be filled with zeros/blanks.

## `FITS_record`

class `astropy.io.fits.``FITS_record`(input, row=0, start=None, end=None, step=None, base=None, **kwargs)

  Bases: `object`

  FITS record class.

  `FITS_record` is used to access records of the `FITS_rec` object. This will allow us to deal with scaled columns. It also handles conversion/scaling of columns in ASCII tables. The `FITS_record` class expects a `FITS_rec` object as input.

  `field`(field)

    Get the field data of the record.

  `setfield`(field, value)

    Set the field data of the record.

## Table Functions

### `new_table()`

`astropy.io.fits.``new_table`(*args, **kwargs)

  Deprecated since version 3.2: Use `FITS_rec.from_columns()` to create a new `FITS_rec` data object from the input columns to pass into the constructor for `BinTableHDU` or `TableHDU` instead.

  Create a new table from the input column definitions.

  Warning: Creating a new table using this method creates an in-memory copy of all the column arrays in the input. This is because if they are separate arrays they must be combined into a single contiguous array.

  If the column data is already in a single contiguous array (such as an existing record array) it may be better to create a BinTableHDU instance directly. See the Astropy documentation for more details.

  Parameters:

  input : sequence of Column or ColDefs objects

  > The data to create a table from.

  header : Header instance

  > Header to be used to populate the non-required keywords.

  nrows : int

  > Number of rows in the new table.

  fill : bool

  > If `True`, will fill all cells with zeros or blanks. If `False`, copy the data from input, undefined cells will still be filled with zeros/blanks.

  tbtype : str or class

  > Table type to be created (BinTableHDU or TableHDU) or the class name as a string. Currently only BinTableHDU and TableHDU (ASCII tables) are supported.

### `tabledump()`

`astropy.io.fits.``tabledump`(filename, datafile=None, cdfile=None, hfile=None, ext=1, clobber=False)

  Dump a table HDU to a file in ASCII format. The table may be dumped in three separate files, one containing column definitions, one containing header parameters, and one for table data.

  Parameters:

  filename : file path, file object or file-like object

  > Input fits file.

  datafile : file path, file object or file-like object (optional)

  > Output data file. The default is the root name of the input fits file appended with an underscore, followed by the extension number (ext), followed by the extension `.txt`.

  cdfile : file path, file object or file-like object (optional)

  > Output column definitions file. The default is `None`, no column definitions output is produced.

  hfile : file path, file object or file-like object (optional)

  > Output header parameters file. The default is `None`, no header parameters output is produced.

  ext : int

  > The number of the extension containing the table HDU to be dumped.

  clobber : bool

  > Overwrite the output files if they exist.

  Notes

  The primary use for the `tabledump` function is to allow editing in a standard text editor of the table data and parameters. The `tcreate` function can be used to reassemble the table from the three ASCII files.

  - datafile: Each line of the data file represents one row of table data. The data is output one column at a time in column order. If a column contains an array, each element of the column array in the current row is output before moving on to the next column. Each row ends with a new line.

    Integer data is output right-justified in a 21-character field followed by a blank. Floating point data is output right justified using ‘g’ format in a 21-character field with 15 digits of precision, followed by a blank. String data that does not contain whitespace is output left-justified in a field whose width matches the width specified in the `TFORM` header parameter for the column, followed by a blank. When the string data contains whitespace characters, the string is enclosed in quotation marks (`""`). For the last data element in a row, the trailing blank in the field is replaced by a new line character.

    For column data containing variable length arrays (‘P’ format), the array data is preceded by the string `'VLA_Length= '` and the integer length of the array for that row, left-justified in a 21-character field, followed by a blank.

    Note

    This format does not support variable length arrays using the (‘Q’ format) due difficult to overcome ambiguities. What this means is that this file format cannot support VLA columns in tables stored in files that are over 2 GB in size.

    For column data representing a bit field (‘X’ format), each bit value in the field is output right-justified in a 21-character field as 1 (for true) or 0 (for false).

  - cdfile: Each line of the column definitions file provides the definitions for one column in the table. The line is broken up into 8, sixteen-character fields. The first field provides the column name (`TTYPEn`). The second field provides the column format (`TFORMn`). The third field provides the display format (`TDISPn`). The fourth field provides the physical units (`TUNITn`). The fifth field provides the dimensions for a multidimensional array (`TDIMn`). The sixth field provides the value that signifies an undefined value (`TNULLn`). The seventh field provides the scale factor (`TSCALn`). The eighth field provides the offset value (`TZEROn`). A field value of `""` is used to represent the case where no value is provided.

  - hfile: Each line of the header parameters file provides the definition of a single HDU header card as represented by the card image.

### `tableload()`

`astropy.io.fits.``tableload`(datafile, cdfile, hfile=None)

  Create a table from the input ASCII files. The input is from up to three separate files, one containing column definitions, one containing header parameters, and one containing column data. The header parameters file is not required. When the header parameters file is absent a minimal header is constructed.

  Parameters:

  datafile : file path, file object or file-like object

  > Input data file containing the table data in ASCII format.

  cdfile : file path, file object or file-like object

  > Input column definition file containing the names, formats, display formats, physical units, multidimensional array dimensions, undefined values, scale factors, and offsets associated with the columns in the table.

  hfile : file path, file object or file-like object (optional)

  > Input parameter definition file containing the header parameter definitions to be associated with the table. If `None`, a minimal header is constructed.

  Notes

  The primary use for the `tableload` function is to allow the input of ASCII data that was edited in a standard text editor of the table data and parameters. The tabledump function can be used to create the initial ASCII files.

  - datafile: Each line of the data file represents one row of table data. The data is output one column at a time in column order. If a column contains an array, each element of the column array in the current row is output before moving on to the next column. Each row ends with a new line.

    Integer data is output right-justified in a 21-character field followed by a blank. Floating point data is output right justified using ‘g’ format in a 21-character field with 15 digits of precision, followed by a blank. String data that does not contain whitespace is output left-justified in a field whose width matches the width specified in the `TFORM` header parameter for the column, followed by a blank. When the string data contains whitespace characters, the string is enclosed in quotation marks (`""`). For the last data element in a row, the trailing blank in the field is replaced by a new line character.

    For column data containing variable length arrays (‘P’ format), the array data is preceded by the string `'VLA_Length= '` and the integer length of the array for that row, left-justified in a 21-character field, followed by a blank.

    Note

    This format does not support variable length arrays using the (‘Q’ format) due difficult to overcome ambiguities. What this means is that this file format cannot support VLA columns in tables stored in files that are over 2 GB in size.

    For column data representing a bit field (‘X’ format), each bit value in the field is output right-justified in a 21-character field as 1 (for true) or 0 (for false).

  - cdfile: Each line of the column definitions file provides the definitions for one column in the table. The line is broken up into 8, sixteen-character fields. The first field provides the column name (`TTYPEn`). The second field provides the column format (`TFORMn`). The third field provides the display format (`TDISPn`). The fourth field provides the physical units (`TUNITn`). The fifth field provides the dimensions for a multidimensional array (`TDIMn`). The sixth field provides the value that signifies an undefined value (`TNULLn`). The seventh field provides the scale factor (`TSCALn`). The eighth field provides the offset value (`TZEROn`). A field value of `""` is used to represent the case where no value is provided.

  - hfile: Each line of the header parameters file provides the definition of a single HDU header card as represented by the card image.