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FTSORT

FTSORT

Name


      FTSORT

Purpose


      Sort a FITS ASCII table according to a specified field

Calling Sequence


      FTSORT,h,tab,[field, REVERSE = ] ;Sort original table header and array
              or
      FTSORT,h,tab,hnew,tabnew,[field, REVERSE =] ;Create new sorted header

Inputs


      H - FITS header (string array)
      TAB - FITS table (byte array) associated with H. If less than 4
              parameters are supplied, then H and TAB will be updated to
              contain the sorted table

Optional Inputs


      FIELD - Field name(s) or number(s) used to sort the entire table.
              If FIELD is a vector then the first element is used for the
              primary sort, the second element is used for the secondary
              sort, and so forth. (A secondary sort only takes effect when
              values in the primary sort field are equal.) Character fields
              are sorted using the ASCII collating sequence. If omitted,
              the user will be prompted for the field name.

Optional Outputs


      HNEW,TABNEW - Header and table containing the sorted tables

Example


      Sort a FITS ASCII table by the 'DECLINATION' field in descending order
      Assume that the table header htab, and array, tab, have already been
      read (e.g. with READFITS or FITS_READ):
      IDL> FTSORT, htab, tab,'DECLINATION',/REVERSE

Optional Input Keyword


      REVERSE - If set then the table is sorted in reverse order (maximum
              to minimum. If FIELD is a vector, then REVERSE can also be
              a vector. For example, REVERSE = [1,0] indicates that the
              primary sort should be in descending order, and the secondary
              sort should be in ascending order.

Example


Side Effects


      A HISTORY record is added to the table header.

Revision History


      Written W. Landsman June, 1988
      Converted to IDL V5.0 W. Landsman September 1997
      New FTINFO calling sequence, added REVERSE keyword, allow secondary sorts
                  W. Landsman May 2000



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