title: Convert value from specific multidimensional array key into key in new array with original arrays as value
body: <p>Basically I just would like to know if there is a built-in way of doing this, that might be faster, like maybe with an array_map callback or something:</p>
  
  <pre><code>function array_rekey($a, $column)
  {
      $array = array();
      foreach($a as $keys) $array[$keys[$column]] = $keys;
      return $array;
  }
  </code></pre>