我正在尝试创建一个基于Arduino的显示屏，显示纽约市地铁北站的下几列火车的时间。 Metro North由MTA运营（MTA是纽约地铁和公共汽车代理商）和I had no trouble creating a similar display for MTA busses.但是，列车数据非常困难。它无法通过URL中的GET命令进行过滤。我必须自己解析数据以获取停止级数据。 （它是按火车组织的。）
我有网页，我可以运行简单的PHP，java等。我想我需要创建一个页面来解析MTA中的“json”/“XML”文件。然后Arduino可以使用简化数据。我可以使用URL和我的api密钥获取实时数据。这就是它的样子：
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喜欢从消防水中喝酒。
这是一种名为GTFS的格式，它应该是“通用的”，但我发现很难找到任何适合它的东西。 For example, simplexml_load_file() in PHP won't work.
Arduinos不适合解析文本。我无法强迫Arduino完成所有工作。
我应该学习什么方法？我对我的服务器没有多少控制权。我无法轻易改变PHP在我的服务器上的运行方式。到目前为止我发现的方法似乎需要扩展和其他我不能做的事情。
答案 0 :(得分：2)
是的，“从消防中喝水”是使用GTFS数据的一个很好的比喻。 GTFS的一个方面是将最少的负载放在运输代理商的系统上，并让应用程序开发人员的系统（您）尽可能多地完成工作。两个部分（具有当前路由信息的“静态”GTFS文件和GTFS实时文件）可以是从“哑”Web服务器（不需要Web应用程序代码）提供的静态数据文件，这使得提供的数据非常可扩展。
某些公交机构（如MTA，如果是公交路线）很不错，可以为您做一些工作，提供XML或JSON API，以便为您提供特定路线的当前实时状态。但是，如果您了解如何处理GTFS数据，则无需依赖其API，您的系统将变得“通用”，能够处理任何提供GTFS实时信息的代理商。
我的猜测是你已经查看了文档，但为了以防万一，这里是参考：https://developers.google.com/transit/
通常，您将使用GTFS文件（包含日历，路线，行程，停靠点和stop_times）和GTFS实时文件（特别是tripUpdate文件）的组合来确定车辆的当前状态是什么与当前旅行的站点有关。它们可能只是为您提供当前行程中车辆的延迟时间，然后您需要查找目标停靠点的每次行程的停止时间并根据相应的延迟进行调整。
然而，MTA再次变得更好，他们只是在实时饲料中给你足够的信息，以显示车辆（例如火车1586）何时将一次到达停靠点（例如停止144）（例如unix）时间1442890020 =星期二，2015年9月22日02:47:00 GMT）和延迟（例如60秒）。
因此，如果您的PHP流程正在尝试为目标站点创建即将到来的出发时间列表，您可以：
json_decode()）对于这个案例，这将是一个快速解决方案。