Online PHP editor | refs for FG9OS

<?php $arr = array(); $arr[] = array('p' => 3, 'id' => 4); $arr[] = array('p' => 3, 'id' => 5); $arr[] = array('p' => 3, 'id' => 6); $arr[] = array('p' => 2, 'id' => 3); $arr[] = array('p' => 1, 'id' => 2); $arr[] = array('p' => 1, 'id' => 7); $arr[] = array('p' => 0, 'id' => 1); $mas = array(); foreach($arr as $ind => $itm) { $mas[$itm['p']][$itm['id']] = 'aaa'.$ind; } print_r($mas);