如何从此数组中提取键=>值对

Question

我有这个数组

[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
                                )
                        )
                )

是否有其他方法来提取id=>值对(注意，在这种情况下，id是子数组中的一个键)比for循环?

Thanks in advance

Answer 1

如果您使用PHP 5.3，您可以使用以下代码(array_reduce):

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

之后，$r包含id => value对。

Edit:使用PHP版本<5.3，你可以这样做:

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