station_distances.py

from time import sleep
import json
import csv
import re
import requests
from omgsecrets import SMART_CHICAGO_URL
from omgsecrets import SMART_CHICAGO_KEY

def distance(station1, station2):

    origins = str(station1["latitude"]) + "," + str(station1["longitude"])
    destinations = str(station2["latitude"]) + "," + str(station2["longitude"])

    r = requests.get(
        SMART_CHICAGO_URL + "?origins=" + origins + "&destinations=" + destinations + "&sensor=false" + "&mode=bicycling&units=imperial&key=" + SMART_CHICAGO_KEY
        )
    if r.status_code != 200:
        # We didn't get a response from Google
        return -1
    result = json.loads(r.content)
    try:
        distance = result["rows"][0]["elements"][0]["distance"]["text"]
    except IndexError, KeyError:
        # We didn't get the response we expected from Google
        return -1
    return distance

if __name__ == "__main__":
    r = requests.get(DIVVY_STATIONS_URL)
    if r.status_code != 200:
        print("ERROR: Couldn't get the station list from Divvy Bikes.")
        exit(1)

    station_data = json.loads(r.content)
    stations = station_data['stationBeanList']

    f = open('station_distances.csv', 'wb')
    csvwriter = csv.writer(f)
    csvwriter.writerow(['stationName1', 'stationName2', 'distance (miles)'])
    for station1 in stations:
        for station2 in stations:
            # Skip this iteration if the stations are the same
            if station1['stationName'] == station2['stationName']:
                continue
            # If the pair (station1, station2) has already been checked,
            # we want to skip checking (station2, station1). We need to 
            # split the input in exactly half, so any given pair is only
            # checked once. One way to do this is by the natural string
            # ordering. In Python, 'a' < 'b' because 'a' comes before 
            # 'b' alphabetically. For any two strings A and B, it's true
            # that either A < B or A > B (unless A is B, but we already
            # check for that). If we check for ordering, we can quickly
            # split our input space in half.
            if station1['stationName'] > station2['stationName']:
                continue
            d = distance(station1, station2)
            csvwriter.writerow([station1['stationName'], station2['stationName'], d])
            print('Distance between {station1} and {station2} is {d}.'.format(
                    station1=station1['stationName'], station2=station2['stationName'], d=d
                ))
            # Let's be nice to Google and wait a tiny bit in between requests
            sleep(0.1)
    f.close()