This function is used to find the intersection between two sets of integers.
Utilities
A vector of values that are found in both set_a and set_b.
set_a: in, required, type=integer A vector of integers. set_b: in, required, type=integer A vector of integers.
count: out, optional, type=integer This keyword contains the number of elements in the intersection vector. indices_a: out, optional, type=integer The indices in vector A where the intersected values appear. Note, this requires the intersected points be unique in each vector. The `Positions` keyword will return ALL the positions of the match, even if there are non-unique matches. indices_b: out, optional, type=integer The indices in vector B where the intersected values appear. This assumes that the intersected points are represented uniquely in the A and B vectors. noresult: in, optional Set this keyword to a value that will be returned from the function if no intersection between the two sets of numbers is found. By default, -1. positions: out, optional, type=integer This keyword returns the positions or locations in A where the values in B appear. success: out, optional, type=boolean This keyword is set to 1 if an intersection was found, and to 0 otherwise.
Here is how to use this program:: IDL> set_a = [1,2,3,4,5] IDL> set_b = [4,5,6,7,8,9,10,11] IDL> Print, cgSetIntersection(set_a, set_b) 4 5 e http://www.idlcoyote.com/tips/set_operations.html for other types of set operations.
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
Change History:: Written by: David W. Fanning, October 31, 2009, from code originally supplied to the IDL newsgroup by Research Systems software engineers. Yikes, bug in original code only allowed positive integers. Fixed now. 2 Nov 2009. DWF. Fixed a problem when one or both of the sets was a scalar value. 18 Nov 2009. DWF. Added a POSITIONS keyword. 30 Nov 2012. DWF. Added a COUNT keyword 3 Dec 2012. DWF. Added INDICES_A and INDICES_B keywords at R.G. Stockwell's suggestion. 13 Dec 2012. DWF.
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