Script to find distance between any two places in globe using google map api

find_distance.py

import os
import sys
import json
import math
import urllib
import urllib2


def find_coords(address):
    """
    This function extracts coordinates from the json response
    given the address.
    """
    url = "https://maps.googleapis.com/maps/api/geocode/json?" 
    data = {'address':address,
        'components':'country:IN'}
    encode_args = urllib.urlencode(data)
    url = url+encode_args
    # print 'url', url
    coords = None
    req = urllib2.Request(url)
    response = None
    jsonenco = None
    try:
        response = urllib2.urlopen(req)
        if response:
            jsonenco = response.read()
        else:
            return -1
    except urllib2.HTTPError as e:
        from time import sleep
        sleep(1.3)
        response = urllib2.urlopen(req)
    
    loc_json = json.loads(jsonenco)
    # print "loc_json: %s" %(loc_json)
    #print loc_json['results']
    if not loc_json['results']:
        return (0.00, 0.00)
    try:
        coords = loc_json['results'][0]['geometry']['location']
    except:
        pass
    # print "coords: %s" %type(coords)
    if coords == None:
        #print "no single coords found"
        coords={}
        coordsa = loc_json['results'][0]['geometry']['bounds']['northeast']
        coordsb = loc_json['results'][0]['geometry']['bounds']['southwest']
        if coordsa['lat']>coordsb['lat']:
            coordslat = ((coordsa['lat']-coordsb['lat'])/2)+coordsb['lat']
            coordslng = ((coordsb['lng']-coordsb['lng'])/2)+coordsb['lng']
            coords = {'lat':coordslat, 'lng':coordslng}
        else:
            coords = loc_json['results'][0]['geometry']['bounds']['northeast']

    # print "coords: %s" %(coords)
    return (coords['lat'], coords['lng'])


def distance_on_unit_sphere(lat1, long1, lat2, long2):
 
    # Convert latitude and longitude to
    # spherical coordinates in radians.
    degrees_to_radians = math.pi/180.0
         
    # phi = 90 - latitude
    phi1 = (90.0 - lat1)*degrees_to_radians
    phi2 = (90.0 - lat2)*degrees_to_radians
         
    # theta = longitude
    theta1 = long1*degrees_to_radians
    theta2 = long2*degrees_to_radians
         
    # Compute spherical distance from spherical coordinates.
 
    # For two locations in spherical coordinates
    # (1, theta, phi) and (1, theta, phi)
    # cosine( arc length ) =
    #    sin phi sin phi' cos(theta-theta') + cos phi cos phi'
    # distance = rho * arc length
     
    cos = (math.sin(phi1)*math.sin(phi2)*math.cos(theta1 - theta2) +
           math.cos(phi1)*math.cos(phi2))
    arc = math.acos( cos )
 
    # Remember to multiply arc by the radius of the earth
    # in your favorite set of units to get length.
    return arc

def find_distance(coords1, coords2):
    """
    Find the rough distance in kilometres between
    coords1 and coords2 using the formula:
    """
    try:
        lat1, long1 = coords1
        lat2, long2 = coords2
        # Calculate difference between two sets of lats and longs. Multiply 
        # by 6373 for distance in kilometres.
        distance = 6373 * distance_on_unit_sphere(lat1, long1, lat2, long2)
    except TypeError:
        distance = -1

    return distance

def format_address(address_string):
    """
    Format the address to create an allowable string
    to feed to Google url.
    """
    stop_list = '!@#$%*&><?/'  #string within single
                                #quotes.
    #address = '+'.join(address_string.split(" "))
    address = address_string
    # print '---------', address
    address = address.encode('ascii', 'ignore')
    address = address.decode('utf-8')
    for stop_char in address:
        if stop_char in stop_list:
            address = ''.join(address.split(stop_char))

    # print "Formatted address: %s" %address

    return address

def feed_addresses(address1, address2):
    """
    Entry point for testing purposes.
    """
    address1 = format_address(address1)
    address2 = format_address(address2)
    coords1 = find_coords(address1)
    coords2 = find_coords(address2)
    distance = find_distance(coords1, coords2)
    return address1, address2, distance


if __name__ == '__main__':
    addresses = [("Bangalore", "Delhi"), ("Kochin", "Chennai")]
    for address1, address2 in addresses:
        print feed_addresses(address1, address2)