Посоветуйте мужики, как можно сократить код.

$a = array();
foreach($res as $row){
  $a[$row['group']][$row['id']][$row['attr']]['name'] = $row['name'];
  $a[$row['group']][$row['id']][$row['attr']]['manager'] = $row['manager'];
  $a[$row['group']][$row['id']][$row['attr']]['date'] = $row['date'];
  ... 
}

//выдаёт ошибку
foreach($res as $row){
  $b = $a[$row['group']][$row['id']][$row['attr']];

  $b['name'] = $row['name'];
  $b['manager'] = $row['manager'];
  $b['date'] = $row['date'];
  ...
  $a[] = $b;
}