- array_intersect: documentation ( source)
- print_r: documentation ( source)
- array_walk: documentation ( source)
<?php
$ids=array(array("a","s"),array("b","s"), array("c","s"), array("e","s"));
$groups=array(array("b","s"),array("c","s"));
array_walk($groups,function($v,$i)use(&$ids){
$ids=array_intersect ($ids,$v);
});
print_r($ids);