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#### A.10.1.12 Plot Table

The Plot Table action takes a URL or filename in the table that points to a table in one of TOCAT's supported formats, and displays a plot window that can plot the data from that table. This is like loading the table (e.g. with the Load Table action) and then opening a plot window in the usual way, but doing it this way does not actually load the table into TOPCAT's list of loaded tables, and every time the action is activated, the data from the last invocation is just replaced with that from the current one (as far as possible - the tables need to have a similar structure for each row). In the plot window, the referenced table is listed first in the Table selector (or selectors, if multiple layers are configured) with the special name "0: Activated". All the currently loaded tables are available in the window as well as the activated one, so you can plot those for comparison in the same window if you want.

The configuration of this action lets you select the type of plot window to use, but other than that does not let you specify in detail how you want the plot to look. However, after you have activated the action once, you can interactively configure the plot as required using all the usual plot options, and subsequent activations of the same action will just update the plot with the data from the newly activated row, without affecting the rest of the configuration. This makes it easy to visually compare column data from tables linked in different rows of the original table. Note however that the details of the plot window configuration are not included when a session is saved.

Configuration for Plot Table action

Configuration:

Table Location:
  Gives the URL or filename of the table to plot for each row. A column name may be selected from the drop-down list, or the expression language may be used to assemble a location string from other columns.
Plot Type:
  Selects which type of plot window will be displayed. The options are as listed in Appendix A.4.
Table Format:
  Selects the file format of the table to load. If the table is in one of the formats that TOPCAT is able to auto-detect (VOTable, FITS, ECSV, CDF, PDS4, Feather) then the default value `(auto)` may be used, otherwise the correct format must be chosen from the list.
Import Parameters:
  If this option is set, then all the values in the activated row of the activated table will be available in the plotted table as table parameters. That means they can accessed from the expression language (e.g. as coordinate expressions) using the param$name syntax.
Allow Preprocessing:
  If set, the "`<syscmd`" or "`|syscmd`" syntax described in Section 4.2 may be used to preprocess the input stream before the table is loaded. This option is usually not required, and has security implications; if it is switched on in an action loaded from a session file, the security panel will be displayed.

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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