我实在看不懂这语句{:isset($data['labels'][$vo['channel_id']])?$data['labels'][$vo['channel_id']]['title']:''} 中$data['labels'][$vo['channel_id']]和$data['labels'][$vo['channel_id']]['title']的意思，有没有知道，帮忙解答一下，感激不尽
