# coyote: CGREVERSEINDICES

- coyote/Utilities
- [Source code]

Description

      Provides a simple way to obtain the data indices from a Histogram REVERSE_INDICES
      vector. Returns a -1 if no indices are available. Check the COUNT keyword for the
      number of indices returned.

Categories

      Utilities

Params

      ri: in, required, type=integer
           The REVERSE_INDICES vector that is returned from the HISTOGRAM command.
      index: in, required, type=integer
           The zero-based index into the REVERSE_INDICES vector from which to obtain
           the indices. For example, an index value of 4 will return the indices in
           the 5th bin (zero based counting) of the histogram.

Keywords

      count: out, optional, type=Long
          The number of indices returned by the function.

Return Value

      indices:
         The indices that were put into the indexth bin of the histogram. A -1
         is returned if no indices are in that particular bin.

Examples

      Used with the HISTOGRAM command::
         IDL> image = cgDemoData(7)
         IDL> h = Histogram(image, REVERSE_INDICES=ri)
         IDL> indices = cgReverseIndices(ri, 4, COUNT=cnt)
         IDL> Help, indices, cnt, h[4]
         INDICES         LONG      = Array[948]
         CNT             LONG      =          948
         <Expression>    LONG      =          948
         IDL> image[indices] = 0

Author

      FANNING SOFTWARE CONSULTING::
          David W. Fanning
          1645 Sheely Drive
          Fort Collins, CO 80526 USA
          Phone: 970-221-0438
          E-mail: david@idlcoyote.com
          Coyote's Guide to IDL Programming: http://www.idlcoyote.com

History

      Written by David W. Fanning at suggestion of Ben Tupper. 7 January 2011.

Copyright

      Copyright (c) 2011, Fanning Software Consulting, Inc.