The code is, unfortunally, wrong. I made a small test program, that shuffles the array a number of times. You should expect all permutations to appear roughly an equal amount of times. However, for a 4 element array, I only get 2 different outcomes: 
#!/usr/bin/perl

use strict;
use warnings 'all';

my %buckets;

my @set = "A" .. "D";

foreach my $run (1 .. 10_000) {
    my @values = @set;
    @values[$_,$a] = @values[$a=rand($_-1),$_] for (reverse 1..$#value
+s);
    $buckets {"@values"} ++;
}

foreach my $key (sort keys %buckets) {
    printf "%4d: %s\n" => $buckets {$key}, $key;
}
printf "%d buckets\n" => scalar keys %buckets;
__END__
4955: B C D A
5045: D C A B
2 buckets

[download]
Luckely, there is a fix, change the rand($_-1) to rand($_+1).

Abigail

In reply to Re: Fisher-Yates shuffle? by Abigail-II
in thread Fisher-Yates shuffle? by BrowserUk

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