Join array values and keys between two php arrays

Question

I need to merge (sort of join) two arrays with both same keys, and in result i want to have the values of the first as keys of the second one :

Example :

$keyArray = [ "key1" => "map1", "key2" => "map1", "key3" => "map2", "key4" => "map3" ];

$valuesArray = [ "key1" => "value1", "key2" => "value2", "key3" => "value3", "key4" => "value3" ];

// expected result :

$mappedResultArray = 
[
  "map1" => [
    "value1",
    "value2"
  ],
  "map2" => [
    "value3"
  ],
  "map3" => [
    "valu3"
  ],
];

I know that this is possible by using php loops/foreach through both arrays, But I want to have a solution using PHP array_* functions (array_map, array_merge ....)

Answer 1

You can do this using array_walk with closure see example below :

$keyArray = [ "key1" => "map1", "key2" => "map1", "key3" => "map2", "key4" => "map3" ];

$valueArray = [ "key1" => "value1", "key2" => "value2", "key3" => "value3", "key4" => "value3" ];

function getMergeByKeys($keyArray, $valueArray) {
    $mapped = [];
    array_walk(
        $keyArray, 
        function($key, $value) use ($valueArray, &$mapped) {
            $mapped[$key][] = $valueArray[$value];
        });
    return $mapped;
}

print_r(getMergeByKeys($keyArray, $valueArray));

It will result :

Array
(
    [map1] => Array
        (
            [0] => value1
            [1] => value2
        )

    [map2] => Array
        (
            [0] => value3
        )

    [map3] => Array
        (
            [0] => value3
        )

)