将二维数组反转

$arr = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];

$arr1 = [
    [7, 4, 1],
    [8, 5, 2],
    [9, 6, 3]
];

function transfer($arr) {
    $res = [];
    foreach ($arr as $v) {
        foreach ($v as $key=>$a) {
            if (!isset($res[$key])) {
                $res[$key] = [];
            }
            array_unshift($res[$key], $a);
        }
    }
    return $res;
}