- var_dump: documentation ( source)
- array_combine: documentation ( source)
- preg_split: documentation ( source)
<?php
$groups="group1, group2, group3,,foo";
$functions="member, member, admin,,bar";
$keys = preg_split('(\s*,+\s*)', $groups);
$values = preg_split('(\s*,+\s*)', $functions);
$array = array_combine($keys, $values);
var_dump($array);