Online PHP editor | refs for RKANK

<?php $items = array( '1_JAN_2017' => array('1' => array(2, 5, 3), '2' => array(3, 2, 6, 9)), '2_JAN_2017' => array('1' => array(3, 9), '3' => array(1, 4, 8)), '3_JAN_2017' => array('4' => array(9), '1' => array(2, 7, 5, 2)), '4_JAN_2017' => array('1' => array(5, 3, 3, 2), '4' => array(4, 9, 8, 5)), '5_JAN_2017' => array('2' => array(8, 5), '5' => array(3, 9, 7)), '6_JAN_2017' => array('5' => array(2, 1, 7, 5), '4' => array(1, 9, 6)), '7_JAN_2017' => array('4' => array(5, 2, 9), '3' => array(4, 1, 6)) ); $sumArray = []; foreach ($items as $date) { foreach ($date as $key => $amounts) { if (!array_key_exists($key, $sumArray)) { $sumArray[$key] = array_sum($amounts); continue; } $sumArray[$key] += array_sum($amounts); } } print_r($sumArray);