Transpose associative array of associative arrays to create associative array of indexed arrays

Question

I need to restructuring my array so that the 2nd level keys are used as first level keys for grouping and the respective values should be pushed into the group's subarray as indexed elements.

This is my array:

[username] => Array
    (
        [3805120] => 5
        [3805121] => 7
    )

[login] => Array
    (
        [3805120] => 9
        [3805121] => 11
    )

I need something like this:

[3805120] => Array
    (
        [0] => 5
        [1] => 9
    )

[3805121] => Array
    (
        [0] => 7
        [1] => 11
    )

I try array_replace_recursive and array_merge_recursive but without success. — didsun, Feb 01 '17 at 08:06
There isn't a magic PHP function that intuitively understands the structure of your array and recognises how you want to change it; you actually have to write a bit of code to do this yourself — Mark Baker, Feb 01 '17 at 08:08
@MarkBaker this is not true. The array_merge_recursive do this job but work only with string not with integer keys. — didsun, Feb 01 '17 at 08:09
Then prefix your keys with something to make them strings, do your array_merge_recursive, and reset the keys afterwards.... but it isn't PHP intuitively restructuring the array for you, it's code to do it yourself — Mark Baker, Feb 01 '17 at 08:17
[Duly written to use array_merge_recursive()](https://3v4l.org/7lGsT) but a simple loop is a lot easier and more easily understood — Mark Baker, Feb 01 '17 at 08:36
Related almost-exact duplicates: https://stackoverflow.com/q/36493112/2943403 , https://stackoverflow.com/q/797251/2943403 — mickmackusa, Aug 19 '21 at 00:49

Ofir Baruch · Accepted Answer · 2017-02-01T08:16:26.930

Pretty simple. You need a nested loop that sets the subarray's keys as the new array's keys and use the [] in order the new values will be "added" to the array with an auto increase value [0,1,...n].

[username] => Array ( [3805120] => 5 [3805121] => 7 )

[login] => Array ( [3805120] => 9 [3805121] => 11 )

// $array is the original array
$newArray = array();

foreach($array as $key => $subarray){
  //key: username, login
  foreach($subarray as $j => $k){
    //j: 3805120, 3805121
    //k: 5,7,9,11
    $newArray[$j][] = $k;
    //1st round: $newArray[3805120][0] = 5, $newArray[3805121][0] = 7
    //2nd round: $newArray[3805120][1] = 9, $newArray[3805121][1] = 11 
  }
}

var_dump($newArray);

Output:

array(2) { [3805120]=> array(2) { [0]=> string(1) "5" [1]=> string(1) "9" } [3805121]=> array(2) { [0]=> string(1) "7" [1]=> string(2) "11" } }

Transpose associative array of associative arrays to create associative array of indexed arrays

1 Answers1