>type llarochelle.pm
use strict;
use warnings;
use Test::More tests=>1;
my $VAR1 = {
          '4' => [
                   '4',
                   '8',
                   '12'
                 ],
          '1' => [
                   '1',
                   '5',
                   '9'
                 ],
          '3' => [
                   '3',
                   '7',
                   '11'
                 ],
          '2' => [
                   '2',
                   '6',
                   '10'
                 ]
        };


my @array = qw(1 2 3 4 5 6 7 8 9 10 11 12);

my $counter = 1;
my $data;

for my $pos (0 .. $#array) {

    $data->{ $pos%4 + 1 }[ int($pos / 4)] = $array[$pos];
}

is_deeply($data, $VAR1);

>perl llarochelle.pm
1..1
ok 1