Online PHP editor | output for 8bYUa

<?php $input = array ( 'bike' => array ( 'id' => 29, 'type' => 'a', 'time' => '9', ), 'car' => array ( 0 => array ( 'id' => 189, 'type' => 'b', 'time' => '18', ), 1 => array ( 'id' => 190, 'type' => 'c', 'time' => '14', ), ), 'plane' => array ( 'id' => 313, 'type' => 'd', 'time' => '20', ), ); $output = []; array_walk_recursive($input, function($value, $key) use (&$output) { if ($key == "id") { $output[] = $value; } }, $output); var_export($output);