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### A.3.1 Data Window

Data Window

The Data Window presents a JTable containing the actual cells of the Apparent Table. You can display it using the Table Data () button when the chosen table is selected in the Control Window's Table List.

You can scroll around the table in the usual way. In most cases you can edit cells by double-clicking in them, though some cells (e.g. ones containing arrays rather than scalars) cannot currently be edited. If it looks like an edit has taken place, it has.

There is a grey column of numbers on the left of the JTable which gives the row index of each row. This is the value of the special Index column, which numbers each row of the original (not apparent) table starting at 1. If the table has been sorted these numbers may not be in order.

Note that reordering the columns by dragging their headings around will change the order of columns in the table's Column Set and hence the Apparent Table.

If you have table with very many columns it can be difficult to scroll the display sideways so that a column you are interested in is in view. In this case, you can go to the Columns Window and click on the description of the column you are after in the display there. This will have the effect of scrolling the Data Window sideways so that your selected column is visible in the centre of the display here.

The following buttons are available in the toolbar:

Subset From Selected Rows
  Defines a new Row Subset consisting of those rows which are currently highlighted. You can highlight a contiguous group of rows by dragging the mouse over them; further contiguous groups can be added by holding the Control key down while dragging. This action is only available when some rows have been selected.
Subset From Unselected Rows
  Defines a new Row Subset consisting of those rows which are visible but currently not highlighted. You can highlight a contiguous group of rows by dragging the mouse over them; further contiguous groups can be added by holding the Control key down while dragging. This action is only available when some rows have been selected.

As well as the normal menu, right-clicking over one of the columns in the displayed table will present a Column Popup Menu, which provides a convenient way to do some things with the column in question:

Replace Column
  Pops up a Synthetic Column dialogue to replace this column with a new synthetic one. The dialogue is initialised with the same name, units etc as the selected column, and with an expression that evaluates to its value. You can alter any of these, and the new column will replace the old one, which will be hidden and renamed by appending a suffix like "_old" to its name.
New Synthetic Column
  Pops up a Synthetic Column dialogue to insert a new synthetic column just after this one.
Sort up
  Sorts the table rows according to ascending value of the contents of the column. Only available if some kind of order (e.g. numeric or alphabetic) can sensibly be applied to the column.
Sort down
  Sorts the table rows according to descending value of the contents of the column. Only available if some kind of order (e.g. numeric or alphabetic) can sensibly be applied to the column.
Hide
  Hides the column. It can be reinstated from the Columns window.
Search Column
  For string-valued columns, this option allows you to search for values in a column. If you select it you will be asked to enter a regular expression, and then any row which matches that expression in this column will be selected (highlighted). If there's just one matching column it will be activated as well. The expression obeys normal regular expression syntax, so for instance you'd enter "`.*XYZ.*`" to find all rows which contain the string "XYZ".
Explode Array Column
  For columns which have an array value with a fixed number of elements, selecting this option will hide the original column and replace it by a set of scalar columns, one for each of its elements. For instance if a column PMAG contains a 5-element vector of type `float[]` representing magnitudes in 5 different bands, selecting this option will hide PMAG and insert 5 new `Float`-type columns PMAG_1...PMAG_5 in its place, each containing one of the magnitudes.

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Next: Parameters Window
Up: Table View Windows
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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@bristol.ac.uk