distance_matrix.py

import json
import urllib.request
from key import API_KEY

def create_distance_matrix(addresses):
    # Distance Matrix API only accepts 100 elements per request, so get rows in multiple requests.
    max_elements = 100
    num_addresses = len(addresses) 
    # Maximum number of rows that can be computed per request
    max_rows = max_elements // num_addresses
    # num_addresses = q * max_rows + r.
    q, r = divmod(num_addresses, max_rows)
    dest_addresses = addresses
    distance_matrix = []
    # Send q requests, returning max_rows rows per request.
    for i in range(q):
        origin_addresses = addresses[i * max_rows: (i + 1) * max_rows]
        response = send_request(origin_addresses, dest_addresses, API_KEY)
        distance_matrix += build_distance_matrix(response)

    # Get the remaining remaining r rows, if necessary.
    if r > 0:
        origin_addresses = addresses[q * max_rows: q * max_rows + r]
        response = send_request(origin_addresses, dest_addresses, API_KEY)
        distance_matrix += build_distance_matrix(response)
    return distance_matrix

def send_request(origin_addresses, dest_addresses, API_key):
    """ Build and send request for the given origin and destination addresses."""
    def build_address_str(addresses):
    # Build a pipe-separated string of addresses
        address_str = ''
        for i in range(len(addresses) - 1):
            address_str += str(addresses[i][0]) + ',' + str(addresses[i][1]) + '|'
        address_str += str(addresses[-1][0]) + ',' + str(addresses[-1][1])
        return address_str

    request = 'https://maps.googleapis.com/maps/api/distancematrix/json?units=imperial'
    origin_address_str = build_address_str(origin_addresses)
    dest_address_str = build_address_str(dest_addresses)
    request = request + '&origins=' + origin_address_str + '&destinations=' + \
                        dest_address_str + '&key=' + API_key
    jsonResult = urllib.request.urlopen(request).read()
    response = json.loads(jsonResult)
    print("\n",response,"\n")
    return response

def build_distance_matrix(response):
    distance_matrix = []
    for row in response['rows']:
        row_list = [row['elements'][j]['duration']['value'] for j in range(len(row['elements']))]
        distance_matrix.append(row_list)
    return distance_matrix

def main(addresses):
    """Entry point of the program"""
    distance_matrix = create_distance_matrix(addresses)
    print(distance_matrix)
    return distance_matrix