- array_intersect_assoc: documentation ( source)
- print_r: documentation ( source)
- array_filter: documentation ( source)
<?php
$arr = array(
1 => array(1,2,3, null, 1, null),
2 => array(1,null,3,null,null)
);
$result=array_intersect_assoc(array_filter($arr[1]), array_filter($arr[2]));
print_r($result);