A.6 Save Window

Save Window

Save Window

The Save Window is used to write tables out, and it is accessed using the Save Table button () in the Control Window's toolbar or File menu. Any table in the Control Window's table list can be written at any time; what is written is the Apparent Table corresponding to the currently selected table, which takes into account any modifications you have made to its data or appearance this session. The current Row Subset and Row Order are displayed in this window as a reminder of what you're about to save; if you modify the values in these selectors you will be modifying the Apparent Table in the usual way.

Any Row Subsets which have been defined on the table in the current session will not be saved themselves, but you can save information about subset membership by creating new boolean columns based on subsets using the "To Column" button () from the Subsets Window.

You can use the Table Output Format selector box to pick the format in which the table will be written from one of the supported output formats. There is no default format, and it won't automatically save to the same format it was loaded from, but if you leave it on "(auto)" it will try to guess the format based on the filename given; for instance if you specify the name "out.fits", a FITS binary table will be written.

You can specify the location of the output table in these ways, which are described in the following sections:

In some cases, saving the table to the same name as it was loaded from can cause problems (e.g. an application crash which loses the data unrecoverably). In other cases, it's perfectly OK. The main case in which it's problematic is when editing an uncompressed FITS binary table on disk. TOPCAT will attempt to warn you if it thinks you are doing something which could lead to trouble; ignore this at your own risk.

There is no option to compress files on output (though you can of course compress them yourself once they have been written).

If the table is large, a progress bar indicating how near the save is to completion will appear. It is not advisable to edit the table during a save operation.

In some cases, when saving a table to a format other than the one from which it was loaded, or if some new kinds of metadata have been added, it may not be possible to express all the data and metadata from the table in the new format. For instance a WDC table can contain data which represent epoch (date), and this cannot be stored in a FITS table. In this case the table may be written with such columns missing. Some message to this effect may be output in this case.