分类树

/**
 * 分类树function
 * @return [type] [description]
 */
function tree($data, $pid = 0,$level = 1)
{
    static $treeList = array();
    foreach ($data as $v) {
        if ($v['pid'] == $pid) {
            $v['level']=$level;
            $treeList[] = $v;//将结果装到$treeList中
            tree($data, $v['id'],$level+1);
        }
    }
    return $treeList;
}