/**
* Group options by a specific column.
*
* @param string $column Column name.
* @param null $callback Optional callback.
*
* @return $this
*/
public function groupBy($column, $callback = null)
{
$options = array();
foreach ($this->options as $key => $value) {
$row = $this->options->row();
$group = $this->groupValue($row[$column], $callback, $row);
$options[$group][$key] = $value;
}
$this->options = new ArrayOptions($options);
return $this;
}
