Online PHP editor | output for HhF63

<?php $a1 = [ ['v' => '13', 't' => '2015-09-08 18:50:00'], ['v' => '25', 't' => '2015-09-08 19:00:00'], ['v' => '34', 't' => '2015-09-08 19:05:00'], ['v' => '24', 't' => '2015-09-08 19:10:00'] ]; $a2 = [ ['v' => '10', 't' => '2015-09-08 18:50:00'], ['v' => '29', 't' => '2015-09-08 18:55:00'], ['v' => '17', 't' => '2015-09-08 19:00:00'] ]; $result =[]; foreach ($a1 as $row) { $result[$row['t']] = [ 'v1' => $row['v'], 'v2' => null, 't' => $row['t'] ]; } foreach ($a2 as $row) { if (isset($result[$row['t']])) { $result[$row['t']]['v2'] = $row['v']; } else { $result[$row['t']] = [ 'v1' => null, 'v2' => $row['v'], 't' => $row['t'] ]; } } ksort($result); var_export(array_values($result));