php - Create seperate sub array based on array key -

i need separate single array sub arrays based on amount of times > appears within array key tell parent category , isn't. note there no limit amount of possible nested parents.

also, if child same name exists, considered unique if has different parent.

my source array structure looks this:

array (   'test parent 2>test child>test sub child' =>    array (     'content_id_4' => null,   ),   'test parent 3' =>    array (     'content_id_4' => null,     'content_id_5' => null,   ),   'test parent>test child>test sub child' =>    array (     'content_id_3' => null,   ),   'test parent 2 no kids' =>    array (     'content_id_3' => null,   ),   'collections>sports' =>    array (     'content_id_2' => null,     'content_id_22' => null,   ),   'collections' =>    array (     'content_id_2' => null,     'content_id_22' => null,     'content_id_6' => null,   ),   'collections>charity' =>    array (     'content_id_6' => null,   ), ) 

in above example, test parent>test child>test sub child mean there parent category test parent has child test child. test child parent , has child called test sub child not have children.

example output required:

array (   'collections' =>    array (     'sports' => null,     'charity' => null,   ),   'test parent' =>    array (     'test child' =>      array (       'test sub child' => null,     ),   ),   'test parent 2 no kids' => null,   'study' =>    array (     'study groups' => null,   ), ) 

i attempted solution can't manage syntax right can create additional array child's children.

i don't require example refactored. looking best solution works.

my example code

$category_structure = array(); foreach($event_categories $main_cat => $content_ids) {      $this_category_list = explode('>', $main_cat);      $this_cat = array();     $this_parent = array_shift($this_category_list);       foreach($this_category_list $cat) {         $this_cat[$this_parent][$cat] = null;     }      $category_structure = array_merge_recursive($this_cat, $category_structure);   } 

this should work you, making sure there no 0 indexed items in result. comes array_merge_recursive think, merging null valued item ones have associative key.

it not elegant p0rnflake's solution though, sure idea.

$collect = array(); $result = array(); $last = ""; foreach($event_categories $main_cat => $content_ids) {     if (strpos($last, $main_cat) === false) {         array_push($collect, explode('>', $main_cat));     }     $last = $main_cat; }  array_walk($collect, function($value) use (&$result) {     $out = array();     $cur = &$out;     foreach ($value $array) {         if (count($value) !== 1) {             $cur[$array] = array();         } else {             $cur[$array] = null;             }         $cur = &$cur[$array];     }     $cur = null;     $result = array_merge_recursive($result, $out); }); var_dump($result);