如何從這個數組

Question

我有這樣的陣列

[InstrumentCategory] => Array 
       (
        [0] => Array 
         (
          [id] => 4 
          [title] => Training 
          [InstrumentsCategory] => Array 
           (
            [id] => 56 
            [instrument_id] => 28 
            [category_id] => 4 
           ) 

         ) 

        [1] => Array 
         (
          [id] => 8 
          [title] => Working time flexibility 
          [InstrumentsCategory] => Array 
           (
            [id] => 57 
            [instrument_id] => 28 
            [category_id] => 8 
           ) 

         ) 

        [2] => Array 
         (
          [id] => 16 
          [title] => Income support for workers 
          [InstrumentsCategory] => Array 
           (
            [id] => 55 
            [instrument_id] => 28 
            [category_id] => 16 
           ) 

         ) 

       ) 

提取關鍵=>值對是否有其他方法來提取ID => value對（注意id在這種情況下是在子的關鍵 - 陣列）比for循環？

預先感謝

Answer 1

如果使用PHP 5.3，則可以使用下面的代碼（array_reduce）：

$r = array_reduce($input_array, 
        function ($res, $cur) { 
         return $res + array($cur['id'] => $cur); 
        }, array()); 

此後，$r包含ID =>值對。

編輯：隨着PHP版本< 5.3，你可以做到以下幾點：

function array_reduce_cb_id ($res, $cur) { 
    return $res + array($cur['id'] => $cur); 
} 

$r = array_reduce($input_array, 'array_reduce_cb_id', array());