Transposing multidimensional arrays in PHP

Question

How would you flip 90 degrees (transpose) a multidimensional array in PHP? For example:

// Start with this array $foo = array(     'a' => array(        1 => 'a1',        2 => 'a2',        3 => 'a3'      ),     'b' => array(        1 => 'b1',        2 => 'b2',        3 => 'b3'      ),     'c' => array(        1 => 'c1',        2 => 'c2',        3 => 'c3'      ) );  $bar = flipDiagonally($foo); // Mystery function var_dump($bar[2]);  // Desired output: array(3) {   ["a"]=>   string(2) "a2"   ["b"]=>   string(2) "b2"   ["c"]=>   string(2) "c2" } 

How would you implement flipDiagonally()?

Edit: this is not homework. I just want to see if any SOers have a more creative solution than the most obvious route. But since a few people have complained about this problem being too easy, what about a more general solution that works with an n^th dimension array?

i.e. How would you write a function so that:

$foo[j][k][...][x][y][z] = $bar[z][k][...][x][y][j] 

?(ps. I don't think 12 nested for loops is the best solution in this case.)

Answer 1

function transpose($array) {     array_unshift($array, null);     return call_user_func_array('array_map', $array); } 

Or if you're using PHP 5.6 or later:

function transpose($array) {     return array_map(null, ...$array); } 

Answer 2

With 2 loops.

function flipDiagonally($arr) {     $out = array();     foreach ($arr as $key => $subarr) {         foreach ($subarr as $subkey => $subvalue) {             $out[$subkey][$key] = $subvalue;         }     }     return $out; }