Python class to farm Stockholms Lokaltrafik of realtime information about when busses are leaving

SlFarm.py

import urllib2
import re

class SlFarm:
    """
    Farms the SL website for information about the arrival times of busses
    Only works for busses at the moment

    Written by Anton Klava, aklava@kth.se


    Usage Example:
        from SlFarm import *

        sl = SlFarm()
        print sl.getRealTime('gullmarsplan')


    Tis 20 Sep 2011 11:14:35
        First version. Things are a bit rough. Regexp is very simple.
        Only works for busses right now. And just a few stations.
        Anton
    """

    urls = {
        'tussmotevagen': 'http://realtid.sl.se/?epslanguage=SV&WbSgnMdl=1860-VHVzc23DtnRldsOkZ2VuIChTdG9ja2hvbG0p-_--_-_-_',
        'kista': 'http://realtid.sl.se/?epslanguage=SV&WbSgnMdl=9302-S2lzdGEgY2VudHJ1bSAoU3RvY2tob2xtKQ%3d%3d-_--_-_-_',
        'gullmarsplan': 'http://realtid.sl.se/?epslanguage=SV&WbSgnMdl=9189-R3VsbG1hcnNwbGFuIChTdG9ja2hvbG0p-_--_-_-_'
    }

    regex = None # Regexp object

    def __init__(self):
        """
        Constructor
        Author: Anton Klava
        """
        self.regex = re.compile(
            "<td.*?>(.+?)</td>",
            re.IGNORECASE|re.MULTILINE|re.DOTALL
        )

    def cleanStr(self, str):
        """
        Simple cleaning of string
        removes tabs, newlines and carrige returns
        Author: Anton Klava
        """
        s = str
        s = s.strip("\t\n\r")
        return s

    def getRealTime(self, station):
        """
        Gets the realtime information for a station
        Station must exist in self.urls.
        Author: Anton Klava
        """
        url = self.urls[station] # Get url for station
        f = urllib2.urlopen(url)
        page = f.read() # Get page contents
        f.close()

        r = self.regex.findall(page)

        l = len(r)
        results = []
        if l!=0 and l%3 == 0:
            for i in range(l/3):
                results.append((
                    self.cleanStr(r[i*3  ]),
                    self.cleanStr(r[i*3+1]),
                    self.cleanStr(r[i*3+2])
                ))

            return results
        else:
            raise Exception(
                "Failed to get realtime results from SL. "+
                "Station: " + station +
                "Url: " + url
            )