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#### A.4.3.4 Stilts Control

The STILTS control () displays the command you would have to issue to the STILTS package to reproduce the currently visible plot. The text is continuously updated to match the currently selected options, layers and navigation status.

STILTS control Command tab

Unlike the other fixed controls, this one does not provide any options to change the current plot, and if you just want to use TOPCAT interactively you don't need to use it at all. But if you want to be able to regenerate the current plot from the command line or a script without setting it up again from a GUI, for instance to generate publishable figures in a reproducible way, you may find it useful.

STILTS is a command-line interface to all the functionality that TOPCAT provides from a Graphical User Interface. Any plot that can be displayed in TOPCAT can also be generated by providing the right parameters to one of the STILTS plotting commands. The STILTS user document provides a full tutorial introduction for these commands, as well as detailed documentation for each of the plotting commands (`plot2plane`, `plot2sky`, ...) and many examples. However, there is a large number of parameters to configure, and the command line to reproduce a complex plot can be quite lengthy, so this control helps you to set up such plots by constructing the command line corresponding to what you can currently see. The text displayed in this panel can either be copied directly to reproduce a plot you have set up interactively, or it can be used as a basis for later adjustments to some of the parameters.

TOPCAT itself contains the STILTS application, so you don't need to install any additional software to use it. You can run it by adding the "`-stilts`" flag to a topcat command, or on a Unix-like OS use the `stilts` script. If you don't already have it, you can download `stilts` to the directory containing your TOPCAT jar file; see also SUN/256. The `Invocation` formatting options described below can also help.

You can use this facility with very little understanding of the details of STILTS. You just need to copy the text (using the Copy button or however that's usually done on your OS) and paste it onto a system command line or into a script. Executing the resulting command should then pop up the current plot in a new window outside of TOPCAT. If it doesn't work, changing some of the Formatting options described below (e.g. setting Invocation to Class-path) may help. To write the result to a graphics file instead of displaying it in a window, just add a parameter like `out=plot.png` to the end of the line. The available graphics output formats are listed in Appendix A.4.2.4.

To understand the generated command and get a better idea of how to tweak the parameters to adjust the plot, you can consult the STILTS user document mentioned above. Just watching how the displayed command changes as you interact with the plot is another way to learn what does what.

This display is available both as a Fixed Control and as a separate window. Both do the same thing, but the window may be convenient if you want to see the way the command text changes as you interact with the GUI in other parts of the fixed or layer controls. To pop up or hide the separate window display, you can either use the Window button at the bottom of the fixed control, or the Export|STILTS Command Window menu item.

Some actions are available from buttons or menu items:

Copy
  Copies the whole command into the system clipboard, for convenience if you want to paste it into an editor or at a shell prompt. You can achieve the same thing using the usual OS-specific gestures if you prefer, e.g. highlighting all the text with the mouse.
Test
  Attempts to execute the displayed command. If successful the reproduced plot will pop up in a new window, and should look the same as the one currently visible in the plot window. This can help to detect some potential problems with the displayed command line, but not all (see more discussion below).
Window
  Displays a separate window containing the information in this control (or hides it if already displayed). This can be convenient to see how the generated command line changes as you interact with the GUI controls.
Error
  If TOPCAT detects some problem with the syntax of the displayed command, this button is enabled and clicking it will show an error message. This can happen if you are trying to refer to a non-algebraic subset by name, or for other reasons including bugs in the code.

NOTE: The STILTS command displayed in this panel is not guaranteed to work from the command line. There are a few reasons for this. The STILTS command tries to name the tables you have loaded into TOPCAT. If they have straightforward filenames this will probably work, but if a plotted table is for example the result of a match operation carried out in the current session, it will not exist on disk yet so it can't be named on the command line. Similarly, using the names of columns or non-algebraic Row Subsets created during the current session may result in command lines that won't work as written, since those values don't exist in the input files. In this case you should prepare a table corresponding to the current TOPCAT state, save that, and edit the STILTS command to use the name of that file for input (or you can reload the file and do plots using that). Subsets as such cannot be saved in this way, but you can achieve much the same thing by storing subset information in a boolean column using the To Column action () from the Subsets Window. Note STILTS does not understand TOPCAT's saved session format. Another thing that can cause trouble is quoted values in algebraic expressions, since STILTS quoting syntax does not always work well on the shell command line. There may also be bugs in the (rather complex) command-generation code that cause the command to fail or to generate a slightly different plot. Hopefully there are not too many of these, but if you find one please report it.

An attempt is made to flag problems in the displayed command line. Constructions that are suspected or expected to cause trouble when executing it are highlighted in a different colour. If the command line itself seems to violate the plotting command syntax, the Error () button will become enabled; clicking on it will display some indication of what's wrong.

However, the best way to test whether a displayed command will work is to copy and paste it onto an actual command line and try to run it. If it works, the plot will show up in a new window. To export this into a graphic file, simply add or modify the `out` parameter (e.g. `out=tc-plot.pdf`).

STILTS control Formatting tab

The Formatting tab gives you various options to adjust how the generated STILTS command is displayed in the Command tab. In the popup window version of this display, these options are available as items in the Formatting menu instead.

You may want to adjust these options for personal taste, or so the output works better with the command-line environment you're using. The basic format is intended to work with a Unix-like shell such as `bash`; in most cases the `name=value` settings should not be too sensitive to shell-specific syntax, but it may be useful for instance to change line ending characters.

The available formatting options are:

Invocation
  Determines how the `stilts` command itself is introduced. Options are:
  - stilts: Just the word "`stilts`", which will work if a command with that name is on the execution path.
  - topcat: The expression "`topcat -stilts`", which will work if the `topcat` command is on the path.
  - Class-path: A longer expression based on the location of the java class files that the currently running TOPCAT application is using. This should work as along as a `java` executable is on the path.
Layer Suffixes
  Determines how the parameters associated with different plot layers are labelled. STILTS groups the parameters corresponding to a given plot layer by using a common suffix, introduced by a parameter with the form "`layer<suffix>=<layer-type>`" (see SUN/252). You can choose any form for these suffixes that does not interfere with the non-suffix parts of the other parameters, and this option allows you to choose how they are generated. Options are:
  - _Numeric: `_1`, `_2`, ...
  - _Alpha: `_A`, `_B`, ...
  - _alpha: `_a`, `_b`, ...
  - Numeric: `1`, `2`, ...
  - Alpha: `A`, `B`, ...
Zone Suffixes
  Determines how suffixes assigned to different plot zones are labelled. Currently, plot zones are only used in the experimental Time Plot Window, so this option does not appear in most plot types. The options are as described for the Layer Suffix selector above.
Table Names
  Determines how tables in TOPCAT are referenced in the generated command line. Options are:
  - Pathname: Full pathname of the input table file, where available. Should be fairly robust for tables loaded from files.
  - Filename: Tail of filename only (no directory name) of the input table file, where available. More compact than Pathname, and should work if the STILTS command is executed in the directory in which all files exist.
  - Label: User-assigned label for the table, as shown in the Control Window.
  - TNum: "`T`" followed by the table identifier. The identifier is the small integer shown in the table list in the Control Window.
Include Defaults
  Parameters in STILTS commands usually have default values, and if the required values are equal to the defaults, those can be omitted from the command line. By default, parameters which take their default values are not displayed in this window. But if you set this checkbox true, even parameters taking their default values are displayed as well. Default-valued parameters are shown in a fainter colour than non-default ones. This may give you a better idea of the various options which are available for the current plot.
Line Endings
  STILTS commands can be quite long and are usually displayed over several screen lines. This control configures how lines breaks are displayed. Options are:
  - plain: just a new line character terminates lines
  - backslash: a backslash ("`\`") is added at the end of each line; suitable for `bash` and other Unix-like shells.
  - caret: a caret ("`^`") is added at the end of each line; suitable for Windows CMD/.bat scripts.
  - backtick: a backtick ("```") is added at the end of each line; suitable for Windows PowerShell
  - none: the command is displayed as one long line
Indent
  Configures the amount of whitespace by which groups of related lines are indented.

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TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page: http://www.starlink.ac.uk/topcat/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk