多维数组值转化为键值数组，并自动归类

[php]代码库

$arr = array(
    '0'=>array(
            'firmware'=>'f1',
            'version'=>'1',
        ),
    '1'=>array(
            'firmware'=>'f1',
            'version'=>'2',
        ),
    '2'=>array(
            'firmware'=>'f1',
            'version'=>'3',
        ),
    '3'=>array(
            'firmware'=>'f2',
            'version'=>'1',
        ),
    '4'=>array(
            'firmware'=>'f2',
            'version'=>'2',
        ),
    );
    $new_arr  =  array();
    foreach ($arr as $row ){
        $new_arr[$row['firmware']][] = $row['version'];
    }
    var_dump($new_arr);