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资源说明：Python module for accessing the CTA BusTracker API
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ctabustracker.py
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A Python module for accessing CTA Bus Tracker information
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About
=====
This implements all of the methods available in the Chicago Transit Authority
Bus Tracker API. (see http://www.transitchicago.com/developers/bustracker.aspx
for more information)
Usage
=====
Setup
-----
Before you can start with anything, you need to create a ctabustracker object,
and set it up with your API key.
::
c = ctabustracker.ctabustracker("i28bcs01q1YV1CfAd1GcVK1q4")
Examples
--------
After instantiating the ctabustracker class, you can get some information out of it.
Getting scheduled arrivals for a stop
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Say you want to figure out when buses are scheduled to arrive at the stop at
76th Street & Ford City Movie Theatre for the #54B South Cicero bus, going
North bound.
First, you'll need to get a list of stops to figure out what stop number is
at that location. Use ``getroute_stops()`` to get a list of stops::
>>> stops = c.getroute_stops("54B", "North Bound")
Note that the case and whitespace in the second parameter must be exact -
title case, and a space between the direction and "bound". [#fixme]_
Next, search through the list of stops to find the one you're looking for::
>>> for stop in stops:
... if (stop.stop_name == "76th Street & Ford City Movie Theatre"):
... break
...
>>> print stop
Stop #: 15935 | Stop name: 76th Street & Ford City Movie Theatre | Latitude: 41.754317884449 | Longitude: -87.733882069588
Then, just pass this stop_id into ``getpredictions_stop()``::
>>> predictions = c.getpredictions_stop(stop.stop_id)
>>> for prediction in predictions:
... print prediction
...
PREDICTION:
Prediction generated at: Sun Dec 19 19:25:00 2010
Type: A
Route: 54B
Direction: North Bound
Route destination: Cermak/Kenton
Stop number: 15935
Stop name: 76th Street & Ford City Movie Theatre
Vehicle number: 1866
Distance away: 4941
Estimated time of arrival: Sun Dec 19 19:32:00 2010
Minutes to arrival (at instantiation): 7
PREDICTION:
Prediction generated at: Sun Dec 19 19:26:00 2010
Type: A
Route: 79
Direction: East Bound
Route destination: Lakefront
Stop number: 15935
Stop name: 76th Street & Ford City Movie Theatre
Vehicle number: 6451
Distance away: 2129
Estimated time of arrival: Sun Dec 19 19:34:00 2010
Minutes to arrival (at instantiation): 8
**Caution**: The "Minutes to arrival" (``Prediction.mins_to_arrival_at_init``)
return value *DOES NOT* update past the initial instantiation of the
Prediction object (created here by calling
``ctabustracker.getpredictions_stop()``). If you want an update, you'll either
need to call this again to generate a new Prediction object (which is the most
accurate, as it will make another call against the BusTracker API), or use
the member function of Prediction ``Prediction.estimated_time_to_arrival()``.
Getting service bulletins for routes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In this example, we're going to get all service bulletins published for routes
21 (Cermak) and 135 (Clarendon/LaSalle Express).
::
>>> bulletins = c.getbulletins_route(21, 135)
>>> for bulletin in bulletins:
... print bulletin
...
SERVICE BULLETIN:
Name: Bus Stop Added - #21 Cermak
Subject: New Bus Stop Added
Detail: Effective Wed, March 10
A new northbound bus stop will be added on the northeast corner at King Drive/25th.
Bus stop is being added for customer convenience.
Brief: None
Priority: Low
AFFECTED SERVICE:
Route number: 21
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 21
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 135
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 136
Route direction: None
Stop number: None
Stop name: None
SERVICE BULLETIN:
Name: Reroute and Temporary Bus Stop Relocation - #21
Subject: Reroute/ Bus Stop Relocation
Detail: Buses will be rerouted for customer convenience to serve the temporary 'L' station entrance on Archer Avenue while we perform station construction to modernize the Cermak-Chinatown station.
Temporary Reroute: Buses will operate in both directions via Cermak, Wentworth, Archer, Clark, and Cermak. Allow extra travel time.
Temporary Bus Stop Relocation:
The eastbound #21 Cermak bus stop on the southwest corner of Cermak/Wentworth will be temporarily discontinued.
Board eastbound buses:
. on Wentworth Avenue a half block north of Cermak Road, or
. on Archer Avenue east of Wentworth, in front of the new auxiliary station entrance.
The westbound bus stop on Cermak Road in front of the Red Line station entrance will be temporarily discontinued. Board westbound buses:
. on the southwest corner of Wentworth/Archer, or
. on the northwest corner of Wentworth/Cermak.
Brief: None
Priority: Low
AFFECTED SERVICE:
Route number: 21
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 21
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 135
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 136
Route direction: None
Stop number: None
Stop name: None
SERVICE BULLETIN:
Name: #135, #136 Temporary Bus Stop Changes
Subject: Wacker Drive Reconstruction
Detail: The northbound bus stop located on the southeast corner at Franklin/Jackson has been temporarily eliminated.
A temporary northbound bus stop has been added on the southeast corner at Jackson/Franklin.
Bus stops have been eliminated or added due to the Wacker Drive Reconstruction Project.
Brief: None
Priority: Low
AFFECTED SERVICE:
Route number: 21
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 21
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 135
Route direction: None
Stop number: None
Stop name: None
AFFECTED SERVICE:
Route number: 136
Route direction: None
Stop number: None
Stop name: None
There are a few things to note that are going on here:
* Each ``Service_Bulletin`` object can contain a ``SB_Service object``. The
``SB_Service`` object contains a CTA service (a stop or a route) that is
affected by this bulletin.
* This is where the CTA BusTracker API specification deviates greatly from the
resulting data. The ``Service_Bulletin.brief`` result appears to never be
used (which is unfortunate for small-screen devices)
* Note that the ``Service_Bulletin.detail`` result has HTML tags in it.
Member Functions
----------------
These should all be documented for the most part by pydoc. Point pydoc
to this module, or see the ctabustracker.html file supplied.
Classes
-------
Be sure to also take a look at the classes themselves. Most are simply
similar to C-style structs, that is, a container for data of differing
types.
.. [#fixme] Denotes an egregrious bug that should be fixed
.. vim: set ft=rst
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