functions group arrays php awesome :)

arrays_group.php

 $original = array
    (
      array
      (
        "dni" => 98989898,
        "email" => "edgra@gmail.com",
        "date" => "2016-09-02 20:58:53",
        "items" => 7
      ),

      array
      (
        "dni" => 9874569,
        "email" => "reyna@gmail.com",
        "date" => "2016-09-02 20:58:54",
        "items" => 1
      ),

      array
      (
        "dni" => 44520253,
        "email" => "llavilla10@gmail.com",
        "date" => "2016-09-02 20:18:12",
        "items" => 1,
      ),

      array
      (
        "dni" => 44520253,
        "email" => "cesar@test.com",
        "date" => "2016-09-02 20:18:05",
        "items" => 2
      ),

print_r(_group_by($original, 'dni'));
print_r(groupArray($original, 'dni'));
print_r(groupsArrays($original, 'dni', ['items'=>array('items')], ['dni','date','email']));

function _group_by($array, $key) {
    $return = array();
    foreach($array as $val) {
      $return[$val[$key]][] = $val;
    }
    return $return;
  }


function groupArray($array, $groupkey)
  {
    if (count($array) > 0) {
      $keys = array_keys($array[0]);
      $removekey = array_search($groupkey, $keys);
      if ($removekey === false)
        return array("Clave \"$groupkey\" no existe");
      else
        unset($keys[$removekey]);
      $groupcriteria = array();
      $return = array();
      foreach ($array as $value) {
        $item = null;
        foreach ($keys as $key) {
          $item[$key] = $value[$key];
        }
        $busca = array_search($value[$groupkey], $groupcriteria);
        if ($busca === false) {
          $groupcriteria[] = $value[$groupkey];
          $return[] = array($groupkey => $value[$groupkey], 'groupeddata' => array());
          $busca = count($return) - 1;
        }
        $return[$busca]['groupeddata'][] = $item;
      }
      return $return;
    } else
      return array();
  }
  
function groupsArrays($array,$indexUnique,$assoGroup,$keepInOne){
   $retour = array();
   $id = $array[0][$indexUnique];
   foreach ($keepInOne as $keep){
     $retour[$id][$keep] = $array[0][$keep];
   }
   foreach ($assoGroup as $cle=>$arrayKey){
     $arrayGrouped = array();
     foreach ($array as $data){
       if($data[$indexUnique] != $id){
         $id = $data[$indexUnique];
         foreach ($keepInOne as $keep){
           $retour[$id][$keep] = $data[$keep];
         }
       }
       foreach ($arrayKey as $val){
         $arrayGrouped[$val] = $data[$val];
       }
       $retour[$id][$cle][] = $arrayGrouped;
       $retour[$id][$cle] = array_unique($retour[$id][$cle],SORT_REGULAR);
     }
   }
   return  $retour;
 }