php - combine two arrays of arrays by key -

how combine 2 arrays of arrays key?

for example:-

array 1:

array (   array (     'id' => '1',     'a' => 'abc'   ),   array (     'id' => '2',     'a' => 'def'   ) ) 

array 2:

array (   array (     'id' => '2',     'b' => '456'   )   array (     'id' => '1',     'b' => '123'   ), ) 

combined array:

array (   array (     'id' => '1',     'a' => 'abc',     'b' => '123'    ),   array (     'id' => '2',     'a' => 'def',     'b' => '456'   ) ) 

the combined array order isn't important, should match based on provided field instead of natural order.

what tried. doesn't efficient though.

public function combinearraysbykey($array_1, $array_2, $key = 'id') {     $combined_array = array();      foreach($array_1 $sub_array_1) {         foreach($array_2 $sub_array_2) {             if ($sub_array_1[$key] == $sub_array_2[$key]) {                 $merged_sub_array = array_merge($sub_array_1, $sub_array_2);                 array_push($combined_array, $merged_sub_array);             }         }     }     return $combined_array; } 

[my code] doesn't efficient though.

you need loop once on each of 2 arrays.

in example function, code inside nested loops ran count($array_1) * count($array_2) times. whereas looping 1 time on each array count($array_1) + count($array_2) times.

^{(obviously, number same when there 2 items in each array savings add up.)}

so, in code, alternative like:

$combined_array = array(); foreach(array($array_1, $array_2) $rows) {     foreach($rows $row) {         $current_key = $row[$key];         if (array_key_exists($current_key, $combined_array)) {             $combined_array[$current_key] += $row;         } else {             $combined_array[$current_key] = $row;         }     } } return $combined_array;