I want to merge a few array into a new array, but group them by the same key value 

When I use this loop 

```
foreach($mrh as $group){
    print_r($group);
};

```

Out put is 

```
Array (
    [2] => 4
)
Array (
    [2] => 5
)
Array (
    [3] => 7
)
Array (
    [3] => 8
)
Array (
    [3] => 10
)

```

My desired output is 

```
array (
    [2] => array(
        [0] => 4,
        [1] => 5
    ),
    [3] => array(
        [0] => 7,
        [1] => 8,
        [2] => 10,
    )
)

```

`array_merge_recursive()` may be useful, but i cant solve it with an `foreach` loop