Online PHP editor | refs for hp1Te

<?php $array = [ ['city' => 'NewYork', 'cash' => '1000'], ['city' => 'Philadelphia', 'cash' => '2300'], ['city' => 'NewYork', 'cash' => '2000'] ]; var_export( array_reduce( $array, function($result, $row) { static $ref; if (!isset($ref[$row['city']])) { $ref[$row['city']] = $row; $result[] = &$ref[$row['city']]; } else { $ref[$row['city']]['cash'] += $row['cash']; } return $result; } ) );