Choose data from Obscat

Choose enables the user to select data by number or selection expression from an observation catalogue (see MAKE OBSCAT). It is an alternative to typing in the full filenames in the read command. The call to CHOOSE clears the previously chosen or read in data, a READ called after a call to choose will add data to the list.

If you have read in filters, (e.g. by SELECT MKF, or FILTER ...commands) then you will be asked whether you want to clear the filters. If you say no, you will retain the filters, but the old data will still be cleared.

You can use a Boolean expression or a range as the argument to choose. If you give a Boolean expression, which must be based on columns in the currently loaded obscat, all those files matching the selection expression will be chosen. The selection expression follows the same syntax as in the select command.

If you give a range, then those rows in the obscat will be chosen. The syntax for the range is that commas delimit ranges, and dashes include all numbers within their termini. One element ranges are legal, and there is one special character: ** = last legal value.


xsel >  choose > <choose_which> <choose_clear>  [quiet]


You can choose by position in the current obscat:

xsel >  choose  1-4,7,8-16,25-**

Or by a Boolean expression applied to the current obscat:

xsel >  choose  "EXPOSURE > 100"

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Last modified: Tuesday, 10-Jan-2023 11:03:00 EST

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