具有相同键的sum数组的最佳实践是什么

For example:

$output = array();
foreach($data as $row) {
    if(!isset($output[$row->foo][$row->bar])) {
        $output[$row->foo][$row->bar] = 0;
    }        
    $output[$row->foo][$row->bar] += $row->value;
}
$output = array();
foreach($data