php multidimensional array sort by key

Sorr_by_key

$arr = [
        "0": [
            "id": 1,
            "schedule_time": "01:01 AM",
            "day": "Thu"
        ],
        "1": [
            "id": 2,
            "schedule_time": "04:00 AM",
            "day": "Sun"
       ],
        "2": [
            "id": 3,
            "schedule_time": "04:15 AM",
            "day": "Tue"
        ],
        "3": [
            "id": 4,
            "schedule_time": "05:00 AM",
            "day": "Sun"
       ],
        "4": [
            "id": 5,
            "schedule_time": "05:17 AM",
            "day": "Tue"
        ]
    ];
$day_map = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'];
    uasort($arr, function($a, $b) use ($day_map) {
        $c = explode(',', $a['day']);
        $d = explode(',', $b['day']);
        for($i = 0, $len = count($c); $i < $len; $i++) {
            $d1 = @array_search($c[$i], $day_map);
            $d2 = @array_search($d[$i], $day_map);
            if($d1 == $d2) {
                continue; // skip, check the next column
            }
            return $d1 - $d2;
        }
    });
  var_dump($arr);