RANPERM Function :: SAS/IML(R) 13.1 User's Guide

RANPERM Function

RANPERM (n) ;

RANPERM (set, <, numperm> ) ;

The RANPERM function generates random permutations of a set with $n$ elements. The random number seed is set by the RANDSEED subroutine.

The first argument, set, can be a scalar or a vector. If set is a scalar, the function returns indices in the range 1– $n$ . If set is a vector, the number of elements of the vector determines $n$ and the RANPERM function returns elements of set, which can be numeric or character.

By default, the RANPERM function returns a single random combination with one row and $n$ columns. If the numperm argument is specified, the function returns a matrix with numperm rows and $n$ columns. Each row of the returned matrix represents a single permutation.

The following statements generate five random permutations of the set $\{ 1, 2, 3\}$ :

call randseed(1234);
n = 3;
p = ranperm(n, 5);
print p;

Figure 24.306: Random Permutations of Three Items

p
1	2	3
3	2	1
3	2	1
3	1	2
3	1	2

Alternatively, the following statements compute five random permutations of an unsorted character vector:

a = ranperm({C B A}, 5);
print a;

Figure 24.307: Random Permutations of a Character Vector

a
B	C	A
B	A	C
C	B	A
B	C	A
B	C	A