If you know there's going to be a large number of swaps, why not make a set of array subscripts and swap those around, then output in whatever the final order is? 
use strict;
use warnings;

my (@nums, @index, $x, $y);

# CREATE MATRIX
push @nums, [1..12] for 1..12;
# CREATE INDEX
@index = (0..11);
# PERFORM RANDOM SWAPS
for (1..20) {
    $x = int rand 12;
    $y = int rand 12;
    swap(\@index, $x, $y);
}
# OUTPUT IN FINAL ORDER
for $x (0..$#nums) {
    print $nums[$y][$_].' ' for (@index);
    print "\n";
}

sub swap {
    my ($p, $x, $y) = @_;
    my $t = $p->[$y];
    $p->[$y] = $p->[$x];
    $p->[$x] = $t;
}

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In reply to Re: swap columns in a 2-dim array by TedPride
in thread swap columns in a 2-dim array by davidj

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