septa_realtime.py

#!/usr/bin/env python

""" Parse JSON real-time bus data from SEPTA:
    http://www3.septa.org/hackathon/
"""

from datetime import datetime, timedelta
import json
import requests
import sys

bus_flds = ['lat', 'lng', 'label', 'VehicleID', 'BlockID', 'Direction', 'destination', 'Offset']
date_fmt = '%B %d, %Y, %I:%M %p'

# to fetch the latest:
r = requests.get('http://www3.septa.org/hackathon/TransitViewAll')
if r.ok:
    j = r.json()
else:
    print('oh noes!  could not fetch realtime data.')
    sys.exit(1)

# or, to read from file:
# f = open('bus.json', 'rb')
# data = f.read()
# f.close()
# j = json.loads(data)

read_at = j.keys()[0]

read_dt = datetime.strptime(read_at, date_fmt)

busct = 0
for itm in j[read_at]:
    inner_keys = itm.keys()
    for key in inner_keys:
        inner_list = itm[key]
        for bus in inner_list:
            # subtract Offset minutes from read_at time to get time bus was at location
            recorded_at = read_dt - timedelta(minutes=int(bus['Offset']))
            # label seems to generally be the same as bus ID
            busct += 1
            print('\n')
            for fld in bus_flds:
                print('%s : %s' % (fld, bus[fld]))

print('\ngot %s buses' % busct)