How can i avoid pass by refrence in array map?

Question

I've this piece of code in which I want to know is there anyway I could avoid pass by reference

public function formatNumbers($numbersData){
    $result = array();
    array_map(
        function($row) use (&$result) {
            $result[$row['GroupId']][$row['Type']] = $row['value'];
        }, $numbersData
    );
    return $result;
}

Input: $numbersData =
Array
(
    [0] => Array
        (
            [GroupId] => 2
            [Type] => 1
            [value] => 82000
        )

    [1] => Array
        (
            [GroupId] => 2
            [Type] => 3
            [value] => 52000
        )

    [2] => Array
        (
            [GroupId] => 2
            [Type] => 4
            [value] => 30105
        )

    [3] => Array
        (
            [GroupId] => 2
            [Type] => 7
            [value] => 13266
        )

)

Output is

Array
(
    [2] => Array
        (
            [1] => 82000
            [3] => 52000
            [4] => 30105
            [7] => 13266
        )

)

I know I can do it using foreach, but I want to know that if there anyway to use array map for this without pass by reference.Any help would be greatly appreciated.

Answer 1

Wrong kind of operation. You're not looking for a mapping of values, you're looking for an array reduction:

return array_reduce($numbersData, function(array $acc, array $row) {
    $acc[$row['GroupId']][$row['Type']] = $row['value'];
    return $acc;
}, []);