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C Library Functions  - M_sets (3)

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NAME

M_sets(3f) - [M_sets::INTRO] functions reminiscent of Matlab set functions

CONTENTS

Synopsis
Description
Example
Authors
License

SYNOPSIS

Procedure names and syntax:

    use M_sets, only : & union, unique, intersect, setdiff, ismember, setxor

DESCRIPTION

Unions, intersection, and set membership

A small subset of set functions reminiscent of Matlab set functions. They currently just work with vectors of default integer kind input and return sets but not the subscripts of the original elements.

It basically uses some simple calls to the M_ordersort(3f) module to provide the functionality that are not tuned for performance and make loose use of memory allocation and space.

Set operations compare the elements in two sets to find commonalities or differences. Currently the sets are arrays of integer numbers.

## Functions

o	union(A,B,setOrder) - Set union of two arrays
o	unique(A,setOrder) - Unique values in array
o	intersect(A,B,setOrder) - Set intersection of two arrays
o	setdiff(A,B,setOrder) - Set difference of two arrays
o	ismember(A,B,setOrder) - Array elements that are members of set array
o	setxor(A,B,setOrder) - Set exclusive OR of two arrays

EXAMPLE

sample program:

   program demo_M_sets
   use M_sets, only: unique, intersect, union, setdiff, ismember, setxor
   character(len=*),parameter :: g=’(*(g0,1x))’
   integer, allocatable      :: A(:)
   integer, allocatable      :: B(:)
   integer, allocatable      :: C(:)

      write(*,g) ’UNIQUE’,’Find the unique elements of vector A.’
       A = [10, -10, 0, 1, 2, 3, 3, 2, 1, -10]
       write(*,g) ’A=’, A
       write(*,g) unique(A)
       write(*,g) unique(A, setOrder=’stable’)
      write(*,g) ’UNION’, ’Find the union of vectors A and B.’
       call setab( [5, 7, 1], [3, 1, 1] )
       write(*,g) union(A,B)
       call setab( [5, 5, 3], [1, 2, 5] )
       write(*,g) union(A, B, ’sorted’)
       write(*,g) union(A, B, ’stable’)
      write(*,g) ’INTERSECT’, ’Find the values common to both A and B.’
       call setab( [7, 1, 7, 7, 4], [7, 0, 4, 4, 0] )
       write(*,g) intersect(A, B)
       write(*,g) intersect(A, B, setOrder=’stable’)
      write(*,g) ’SETDIFF’,’Find the values in A that are not in B.’
       call setab( [3, 6, 2, 1, 5, 1, 1], [2, 4, 6] )
       write(*,g) setdiff(A, B)
       call setab( [4, 1, 3, 2, 5], [2, 1])
       write(*,g) setdiff(A, B, ’sorted’)
       write(*,g) setdiff(A, B, ’stable’)
      write(*,g) ’ISMEMBER’, ’Determine which elements of A are also in B.’
       call setab( [5,3,4,2], [2,4,4,4,6,8] )
       write(*,g) ismember(A,B)
      write(*,g) ’SETXOR’,’Find values of A and B not in their intersection.’
       call setab( [5,1,3,3,3], [4,1,2] )
       write(*,g) setxor(A,B)
       write(*,g) setxor(A,B,’stable’)

   contains
   subroutine setab(ain,bin)
   integer,intent(in) :: ain(:)
   integer,intent(in) :: bin(:)
      A=ain
      B=bin
      write(*,g) ’A=’, A
      write(*,g) ’B=’, B
   end subroutine setab

   end program demo_M_sets

Results:

 > UNIQUE Find the unique elements of vector A.
 > A= 10 -10 0 1 2 3 3 2 1 -10
 > -10 0 1 2 3 10
 > 10 -10 0 1 2 3
 > UNION Find the union of vectors A and B.
 > A= 5 7 1
 > B= 3 1 1
 > 1 3 5 7
 > A= 5 5 3
 > B= 1 2 5
 > 1 2 3 5
 > 5 3 1 2
 > INTERSECT Find the values common to both A and B.
 > A= 7 1 7 7 4
 > B= 7 0 4 4 0
 > 4 7
 > 7 4
 > SETDIFF Find the values in A that are not in B.
 > A= 3 6 2 1 5 1 1
 > B= 2 4 6
 > 1 3 5
 > A= 4 1 3 2 5
 > B= 2 1
 > 3 4 5
 > 4 3 5
 > ISMEMBER Determine which elements of A are also in B.
 > A= 5 3 4 2
 > B= 2 4 4 4 6 8
 > 0 0 1 1
 > SETXOR Find values of A and B not in their intersection.
 > A= 5 1 3 3 3
 > B= 4 1 2
 > 2 3 4 5
 > 5 3 4 2

AUTHORS

John S. Urban, 2023-07-20

LICENSE

CC0-1.0

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Nemo Release 3.1

M_sets (3)

July 22, 2023

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