Cartesian Product of multiple arrays associate with existing array php

I want to generate a form table with all combinations between attribute and attribute values. I use possible_combs() - function to generate them function possible_combos($groups, $prefix='') { $result = array(); $group = array_shift($groups); foreach($group as $selected) { if($groups) { $result = array_merge($result, possible_combos($groups, $prefix .$selected.', ')); } else { $result[] = [ 'combination_string' => $prefix.$selected, ]; } } return $result; } BUT, i want to associate product_id for existing combs. I want to know the logic behind this, how can i merge or find in comb_string to know when combination has product_id and when i have to create new one by adding product_id - 0.