Online PHP editor | output for ZloLB

<?php $distance_covered = array( '1_JAN_2017' => array('DRIVER_1' => array(2, 5, 3),'DRIVER_2' => array(3, 2, 6, 9)), '2_JAN_2017' => array('DRIVER_1' => array(3, 9), 'DRIVER_3' => array(1, 4, 8)), '3_JAN_2017' => array('DRIVER_4' => array(9), 'DRIVER_1' => array(2, 7, 5, 2)), '4_JAN_2017' => array('DRIVER_1' => array(5, 3, 3, 2), 'DRIVER_4' => array(4, 9, 8, 5)), '5_JAN_2017' => array('DRIVER_2' => array(8, 5), 'DRIVER_5' => array(3, 9, 7)), '6_JAN_2017' => array('DRIVER_5' => array(2, 1, 7, 5), 'DRIVER_4' => array(1, 9, 6)), '7_JAN_2017' => array('DRIVER_4' => array(5, 2, 9), 'DRIVER_3' => array(4, 1, 6)), ); var_export(array_map('array_sum', array_merge_recursive(...array_values($distance_covered))));