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
 )
)