PHP Category Iteration

$catrefs = array();
$catlist = array();
foreach($categories as $tmp) {

        $thisref = &$catrefs[ $tmp['id'] ];
        $thisref['parent_id'] = $tmp['parent'];
        $thisref['name'] = $tmp['name'];
        $thisref['products'] = $tmp['products'];
        $thisref['totals'] = $tmp['products'];

        if($tmp['parent'] == 0) {

                $catlist[ $tmp['id'] ] = & $thisref;
        }
        else {

                $catrefs[ $tmp['parent'] ]['children'][ $tmp['id'] ] = &$thisref;
        }
}