請問如何用鍵名分組？

$arr1 = array ('0' => array ('fid' => 1, 'tid' => 1 , 'name' =>'Name2' ),'2' => array ('fid' => 1, 'tid' => 1,  'name' =>'Name1' ),'1' => array ('fid' => 1, 'tid' => 5 , 'name' =>'Name3' ),'3' => array ('fid' => 1, 'tid' => 7 , 'name' =>'Name4' ),'4' => array ('sid' => 2, 'tid' => 9,  'name' =>'Name5' )，'5' => array ('cid' => 2, 'tid' => 9,  'name' =>'Name5' ));

請問有什麼最快的方法可以以鍵名fid,sid,cid分組。

回複討論(解決方案)

$arr1 = array ('0' => array ('fid' => 1, 'tid' => 1 , 'name' =>'Name2' ),'2' => array ('fid' => 1, 'tid' => 1,  'name' =>'Name1' ),'1' => array ('fid' => 1, 'tid' => 5 , 'name' =>'Name3' ),'3' => array ('fid' => 1, 'tid' => 7 , 'name' =>'Name4' ),'4' => array ('sid' => 2, 'tid' => 9,  'name' =>'Name5' ),'5' => array ('cid' => 2, 'tid' => 9,  'name' =>'Name5' ));foreach($arr1 as $v) {  $k = key($v);  $res[$k][] = $v;}print_r($res);

Array(    [fid] => Array        (            [0] => Array                (                    [fid] => 1                    [tid] => 1                    [name] => Name2                )            [1] => Array                (                    [fid] => 1                    [tid] => 1                    [name] => Name1                )            [2] => Array                (                    [fid] => 1                    [tid] => 5                    [name] => Name3                )            [3] => Array                (                    [fid] => 1                    [tid] => 7                    [name] => Name4                )        )    [sid] => Array        (            [0] => Array                (                    [sid] => 2                    [tid] => 9                    [name] => Name5                )        )    [cid] => Array        (            [0] => Array                (                    [cid] => 2                    [tid] => 9                    [name] => Name5                )        ))

考慮到各成員數組的鍵名排列可能不一致，即 sid 可能在 name 後面
可將
$k = key($v);
改為
$k = key(array_intersect_key(array('fid' => '', 'sid' => '', 'cid' => ''), $v));

