On Tue, 15 Aug 2006, Peter W. Draper wrote:
> Hi Mark,
>
> Clive's right and GAIA uses the Skycat parsing for TAB tables. In Skycat
> only the ra_col/dec_col and x_col/y_col parameters can be set to -1, the
> id_col value must either have a column set, or it will use the first
> column, regardless. The reason for this is nothing to do with any
> standards (where they exist), just the practicalities of the
> implementation which requires a column of identifiers for controlling row
> selection (these should be unique but don't need to be just to get the
> plotting to work). When possible during an import of a table without an
> obvious identifier column I just create a simple integer index column.
thanks - I'd figured that adding a new ID column where necessary was
the best way round but it's nice to be reassured that -1 values are
OK for ra_col and dec_col. Where I can't find an X/Y columns I just
don't write x_col/y_col parameters rather than setting them -1,
I presume that's OK.
Mark
--
Mark Taylor Astronomical Programmer Physics, Bristol University, UK
[log in to unmask] +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/
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