transpose array 2d

<?php
$input = array(
'januari'=>array(2,5,4,7,8,2),
'februari'=>array(6,2,8,5,4,3),
'maret'=>array(7,6,3,8,9,3)
);
echo "<pre>---Input--\n";
print_r($input);
array_unshift($input, null);
$output = call_user_func_array('array_map', $input);

echo "---Output--\n";
print_r($output);

hasilnya:
=========

---Input--
Array
(
    [januari] => Array
        (
            [0] => 2
            [1] => 5
            [2] => 4
            [3] => 7
            [4] => 8
            [5] => 2
        )

    [februari] => Array
        (
            [0] => 6
            [1] => 2
            [2] => 8
            [3] => 5
            [4] => 4
            [5] => 3
        )

    [maret] => Array
        (
            [0] => 7
            [1] => 6
            [2] => 3
            [3] => 8
            [4] => 9
            [5] => 3
        )

)
---Output--
Array
(
    [0] => Array
        (
            [0] => 2
            [1] => 6
            [2] => 7
        )

    [1] => Array
        (
            [0] => 5
            [1] => 2
            [2] => 6
        )

    [2] => Array
        (
            [0] => 4
            [1] => 8
            [2] => 3
        )

    [3] => Array
        (
            [0] => 7
            [1] => 5
            [2] => 8
        )

    [4] => Array
        (
            [0] => 8
            [1] => 4
            [2] => 9
        )

    [5] => Array
        (
            [0] => 2
            [1] => 3
            [2] => 3
        )

)