FTAB_EXT
Name
FTAB_EXT
Purpose
Routine to extract columns from a FITS (binary or ASCII) table.
Calling Sequence
FTAB_EXT, name_or_fcb, columns, v1, [v2,..,v9, ROWS=, EXTEN_NO= ]
Inputs
name_or_fcb - either a scalar string giving the name of a FITS file
containing a (binary or ASCII) table, or an IDL structure
containing as file control block (FCB) returned by FITS_OPEN
If FTAB_EXT is to be called repeatedly on the same file, then
it is quicker to first open the file with FITS_OPEN, and then
pass the FCB structure to FTAB_EXT
columns - table columns to extract. Can be either
(1) String with names separated by commas
(2) Scalar or vector of column numbers
Outputs
v1,...,v30 - values for the columns. Up to 30 columns can be extracted
Optional Input Keywords
ROWS - scalar or vector giving row number(s) to extract
Row numbers start at 0. If not supplied or set to
-1 then values for all rows are returned
EXTEN_NO - Extension number to process. If not set, then data is
extracted from the first extension in the file (EXTEN_NO=1)
Examples
Read wavelength and flux vectors from the first extension of a
FITS file, 'spec.fit'. Using FTAB_HELP,'spec.fit' we find that this
information is in columns named 'WAVELENGTH' and 'FLUX' (in columns 1
and 2). To read the data
IDL> ftab_ext,'spec.fit','wavelength,flux',w,f
or
IDL> ftab_ext,'spec.fit',[1,2],w,f
Procedures Called
FITS_READ, FITS_CLOSE, FTINFO, FTGET(), TBINFO, TBGET()
History
version 1 W. Landsman August 1997
Converted to IDL V5.0 W. Landsman September 1997
Improve speed processing binary tables W. Landsman March 2000
Use new FTINFO calling sequence W. Landsman May 2000
Don't call fits_close if fcb supplied W. Landsman May 2001
Use STRSPLIT to parse column string W. Landsman July 2002
Cleanup pointers in TBINFO structure W. Landsman November 2003
Avoid EXECUTE() if V6.1 or later W. Landsamn December 2006
Assume since V6.1 W. Landsman June 2009
Read up to 30 columns W.L. Aug 2009