setunion.pro
5.18 KB
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;+
; NAME:
; SETUNION
;
; PURPOSE:
;
; This function is used to find the union between two sets of integers.
;
; AUTHOR:
;
; FANNING SOFTWARE CONSULTING
; David Fanning, Ph.D.
; 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/
;
; CATEGORY:
;
; Utilities
;
; CALLING SEQUENCE:
;
; union = SetUnion(set_a, set_b)
;
; RETURN VALUE:
;
; union: A vector of values that are found in the combined integer sets.
;
; ARGUMENTS:
;
; set_a: A vector of integers.
;
; set_b: A vector of integers.
;
; KEYWORDRS:
;
; None.
;
; EXAMPLE:
;
; IDL> set_a = [1,2,3,4,5]
; IDL> set_b = [4,5,6,7,8,9,10,11]
; IDL> Print, SetUnion(set_a, set_b)
; 1 2 3 4 5 6 7 8 9 10 11
;
; See http://www.idlcoyote.com/tips/set_operations.html for other types of set operations.
;
; NOTES:
;
; If you read the Set Operations article pointed to above, you will see quite a lot of
; discussion about what kinds of algorithms are faster than others. The Histogram
; algorithms implemented here are sometimes NOT the fastest algorithms, especially
; for sparse arrays. If this is a concern in your application, please be sure to read
; that article.
;
; One alternative for the SetUnion algorithm, provided by Maarten Sneep, is simply this:
;
; superset = [set_a, set_b]
; union = superset[Uniq(superset, Sort(superset))]
;
; MODIFICATION HISTORY:
;
; Written by: David W. Fanning, November 25, 2009, from code originally supplied to the IDL
; newsgroup by Research Systems software engineers.
;-
;******************************************************************************************;
; Copyright (c) 2009, by Fanning Software Consulting, Inc. ;
; All rights reserved. ;
; ;
; Redistribution and use in source and binary forms, with or without ;
; modification, are permitted provided that the following conditions are met: ;
; ;
; * Redistributions of source code must retain the above copyright ;
; notice, this list of conditions and the following disclaimer. ;
; * Redistributions in binary form must reproduce the above copyright ;
; notice, this list of conditions and the following disclaimer in the ;
; documentation and/or other materials provided with the distribution. ;
; * Neither the name of Fanning Software Consulting, Inc. nor the names of its ;
; contributors may be used to endorse or promote products derived from this ;
; software without specific prior written permission. ;
; ;
; THIS SOFTWARE IS PROVIDED BY FANNING SOFTWARE CONSULTING, INC. ''AS IS'' AND ANY ;
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES ;
; OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT ;
; SHALL FANNING SOFTWARE CONSULTING, INC. BE LIABLE FOR ANY DIRECT, INDIRECT, ;
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED ;
; TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; ;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ;
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT ;
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS ;
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. ;
;******************************************************************************************;
FUNCTION SetUnion, set_a, set_b
Compile_Opt StrictArr, DefInt32
; Error handling.
Catch, theError
IF theError NE 0 THEN BEGIN
Catch, /CANCEL
void = Error_Message()
RETURN, ""
ENDIF
; Check parameters.
IF N_Params() NE 2 THEN Message, 'Two input parameters or sets are required.'
; The input sets must be integers.
IF (Size(set_a, /TYPE) GT 3) AND (Size(set_a, /TYPE) LT 12) THEN $
Message, 'Set A must be an integer array.'
IF (Size(set_b, /TYPE) GT 3) AND (Size(set_b, /TYPE) LT 12) THEN $
Message, 'Set B must be an integer array.'
; If either of the sets is a scalar, make it a vector.
IF N_Elements(set_a) EQ 1 && (Size(set_a))[0] EQ 0 THEN set_a = [set_a]
IF N_Elements(set_b) EQ 1 && (Size(set_b))[0] EQ 0 THEN set_b = [set_b]
; Find and return the unique indices in the two sets.
h = Histogram([set_a, set_b], OMIN=omin)
RETURN, Where(h GT 0) + omin
END