php 二维数组根据某个字段排序

function list_sort_by($list, $field, $sortby = 'desc')
{
    if (is_array($list))
    {
        $refer = $resultSet = array();
        foreach ($list as $i => $data)
        {
            $refer[$i] = &$data[$field];
        }
        switch ($sortby)
        {
            case 'asc': // 正向排序
                asort($refer);
                break;
            case 'desc': // 逆向排序
                arsort($refer);
                break;
            case 'nat': // 自然排序
                natcasesort($refer);
                break;
        }
        foreach ($refer as $key => $val)
        {
            $resultSet[] = &$list[$key];
        }
        return $resultSet;
    }
    return false;
}