当每个值也是数组时,如何翻转数组？

Question

我将如何翻转数组并建立所有值和键之间的关系？例如:

我想把这个转过来:

Array ( 
[11913] => Array ( 
            [0] => 4242 
            [1] => 3981 
    ) 
[9878] => Array ( 
            [0] => 2901 
            [1] => 3981 
    ) 
[11506] => Array ( 
            [0] => 3981 
            [1] => 2901 
    ) 
 )

进入:

Array ( 
    [3981] => Array ( 
            [0] => 11506 
            [1] => 9878 
            [2] => 11913 
        ) 
    [2901] => Array ( 
            [0] => 11506 
            [1] => 9878 
        ) 
    [4242] => Array ( 
            [0] => 11913 
        ) 
     )

是否有任何PHP功能已经自动执行此操作？如果不是什么方法可以解决这个问题？似乎无法绕过它.

Answer 1

干得好.

$final_array = array();
foreach($initial_array as $key => $val){
    foreach($val as $v){
        $final_array[$v][] = $key;
    }
}