怎么对多维数组的键名进行排序

如何对多维数组的键名进行排序
比如
$families = array
(
  "Griffin"=>array
  (
  "Peter"=>50
  ),
  "Brown"=>array
  (
  "Cleveland"=>30
  )
);
正序排，排完序后的键名和对应的键值不变，形如下面的形式：
$families = array
(
  
  "Brown"=>array
  (
  "Cleveland"=>30
  )，
"Griffin"=>array
  (
  "Peter"=>50
  )
);

------解决方案--------------------

PHP code

foreach($families as $v)       foreach($v as $vl) $p[]=$vl;      array_multisort($p,SORT_ASC,$families);      print_r($families);