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 ....)

Most of array_ functions do not consider array keys. This means that you'll have to use something like array_keys which is useless. — u_mulder
– u_mulder, Commented Feb 4, 2022 at 13:53
array_combine() is the closest but it doesn't handle the merging of multiple values for one same key, so typically you would only get 'map1' => 'value2' instead of 'map1' => ['value1', 'value2']. So I think you'll probably have to write your own code to do this "merging" if the key already has a value for it. — Patrick Janser
– Patrick Janser, Commented Feb 4, 2022 at 13:58
foreach is the most performant solution because it would be a O(N) solution, no need to play smart other way. — ikhvjs
– ikhvjs, Commented Feb 4, 2022 at 13:58
Equivalent page with one-to-one relationships: Replace keys in an array based on another lookup/mapping array — mickmackusa
– mickmackusa ♦, Commented Oct 7, 2022 at 23:08

Mohamed23gharbi · Accepted Answer · 2022-02-04 13:59:27Z

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 ) )

Nice solution! It's neat. But well, I finally Googled and using a foreach seems still faster.

Angel Deykov · Accepted Answer · 2022-02-04 14:09:18Z

A simple foreach is what you need

$keyArray = [ "key1" => "map1", "key2" => "map1", "key3" => "map2", "key4" => "map3" ]; $valuesArray = [ "key1" => "value1", "key2" => "value2", "key3" => "value3", "key4" => "value3" ]; $newArr = []; foreach( $keyArray as $key => $value ){ $newArr[$value][] = $valuesArray[$key]; } print_r($newArr);

This results in:

Array ( [map1] => Array ( [0] => value1 [1] => value2 ) [map2] => Array ( [0] => value3 ) [map3] => Array ( [0] => value3 ) )

lukas.j · Accepted Answer · 2022-02-04 14:19:13Z

$keys = [ "key1" => "map1", "key2" => "map1", "key3" => "map2", "key4" => "map3" ]; $values = [ "key1" => "value1", "key2" => "value2", "key3" => "value3", "key4" => "value3" ]; $result = array_reduce( array_merge_recursive($keys, $values), function ($carry, $item) { $carry[$item[0]][] = $item[1]; return $carry; }, [] ); print_r($result);

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