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I want to use a GTFS feed in Google Maps, but I don't know how to. I want to display the buses available from a route. Just so you know, I'm planning on implementing the Google Map I make in a Visual C# application.

user2481787
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This is a very general question, so my answer will necessarily be general as well. If you can provide more detail about what you're trying to accomplish I'll try to offer more specific help.

At a high level, the steps for working with a GTFS feed are:

  1. Parse the data. From the GTFS feed's URL you'll obtain a ZIP file containing a set of CSV files. The format of these files is specified in Google's GTFS reference, and most languages already have a CSV-parsing library available that can be used to read in the data. Additionally, for some languages there are GTFS-parsing libraries available that will return data from these files as objects; it looks like there's one available for C#, gtfsengine, you might want to check out.

  2. Load the data. You'll need to store the data somewhere, at least temporarily, to be able to work with it. This could simply be a data structure in memory (particularly if you've written your own parsing code) but since larger feeds can take some time to read you'll probably want to look at using a relational database or some other kind of storage you can serialize to disk. In the application I'm developing, a separate process parses and loads GTFS data into a relational database in one pass.

  3. Query the data. Obviously how you do this will depend on the method you use for storing the data and the purpose of your application. If you're using a relational database, you will typically have one table per GTFS entity (or CSV file) on which you can construct indices and against which you can execute SQL queries. If you're working with objects in memory, you might construct a hash-table index in memory as well and query that to find the data you need.