use strict;
use warnings;

use Data::Dumper;

my $arr = [
    10,
    7,
    5,
    10,
    50,
    70,
    75,
    72,
    79,
    80
];

my $avg;
foreach my $i ($#$arr)
{
    $avg = ($i + ($avg ? $avg : $i)) / 2;
}
print "avg [$avg]\n";

@$arr = sort {$a <=> $b} @$arr;

my $store;
foreach my $i (0 .. $#$arr)
{
    $store->[$i]{num} = $arr->[$i];
    $store->[$i]{thresh} = $avg;

    foreach my $store_i (0 .. $#$store)
    {
        if (abs($arr->[$i] - $store->[$store_i]{num}) <= $store->[$i]{thresh})
        {
            push @{$store->[$i]{group}}, $arr->[$i];
        }
    }
}

print Dumper($store);