#!/bin/perl
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) {

        print $array[$pos],"\n";
        push @{$data->{$counter}}, $array[$pos];
        if ($counter == 4) {
                $counter = 1;
        } else {
                $counter++;
        }

};

use Data::Dumper;
print Dumper($data);

##</code><code>##

 
1
2
3
4
5
6
7
8
9
10
11
12
$VAR1 = {
          '4' => [
                   '4',
                   '8',
                   '12'
                 ],
          '1' => [
                   '1',
                   '5',
                   '9'
                 ],
          '3' => [
                   '3',
                   '7',
                   '11'
                 ],
          '2' => [
                   '2',
                   '6',
                   '10'
                 ]
        };