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### 4.4 Table filter commands (`cmd_*`)

The STILTS table filters documented in Section 6.1 are available in JyStilts as table methods which start with the "`cmd_`" prefix. The return value when calling the method on a table object is another table object. The arguments, which are the same as those required for the command-line version, are supplied as a list of unnamed arguments of the `cmd_*` function. In general the arguments are strings, but numbers are accepted where appropriate. Use the python `help` command to see the usage of each method.

So, to use the `tail` filter to select only the last ten lines of a table, you can write:

       table.cmd_tail(10)

To set units of "Hz" for some columns using the `colmeta` filter write:

       table.cmd_colmeta('-units', 'Hz', 'AFREQ BFREQ CFREQ')

Note that where a filter argument is a space-separated list it must appear as a single argument in the filter invocation, just as in command-line STILTS.

The filter commands are also available as module functions. This means that

       stilts.cmd_head(table, 10)

and

       table.cmd_head(10)

have exactly the same meaning. It's a matter of taste which you prefer.

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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk