spatial-optimization

This notebook illustrates the use of the Google Maps API to determine the optimum route given a list of addresses

Task: Find the best route for a vehicle to travel between the following locations:

115 St Andrew’s Drive, Durban North, KwaZulu-Natal, South Africa
67 Boshoff Street, Pietermaritzburg, KwaZulu-Natal, South Africa
4 Paul Avenue, Fairview, Empangeni, KwaZulu-Natal, South Africa
166 Kerk Street, Vryheid, KwaZulu-Natal, South Africa
9 Margaret Street, Ixopo, KwaZulu-Natal, South Africa
16 Poort Road, Ladysmith, KwaZulu-Natal, South Africa

Steps to follow

Obtain an API key

If you do not already have one, please obtain an API key by following the instructions at:

Enable the various APIs on your console

apikey = '################################' # Please enter your own

Geocoding

Geocoding is the process of converting addresses (like "1600 Amphitheatre Parkway, Mountain View, CA") into geographic coordinates (like latitude 37.423021 and longitude -122.083739), which you can use to place markers on a map, or position the map.

Please see: Google Maps Geocoding intro for more details

import pandas as pd # pandas - a powerful data analysis and manipulation library for Python
import requests # Requests is an HTTP library, written in Python, for human beings.

At present, we have been given a short list of addresses, so we will keep things nice and simple. If more addresses were given in a file or other format, we will have to import it accordingly.

 address_list = ["115 St Andrew’s Drive, Durban North, KwaZulu-Natal, South Africa",
                "67 Boshoff Street, Pietermaritzburg, KwaZulu-Natal, South Africa",
                "4 Paul Avenue, Fairview, Empangeni, KwaZulu-Natal, South Africa",
                "166 Kerk Street, Vryheid, KwaZulu-Natal, South Africa",
                "9 Margaret Street, Ixopo, KwaZulu-Natal, South Africa",
                "16 Poort Road, Ladysmith, KwaZulu-Natal, South Africa"]

Geocoding API Request Format

A Geocoding API request takes the following form:

Google Maps Geocoding Formatting where outputFormat may be either of the following values:

json (recommended) indicates output in JavaScript Object Notation (JSON); or
xml indicates output in XML

results = [] locations_latitude = [] locations_longitude = [] formatted_address = [] for location_string in address_list: r = requests.get('https://maps.googleapis.com/maps/api/geocode/json?address="%s"&key=%s'% (location_string, apikey)) result = r.json()['results'] location = result[0]['geometry']['location'] locations_longitude.append(location['lng']) locations_latitude.append(location['lat']) formatted_address.append(result[0]['formatted_address']) results.append(result)
The code in this cell is based roughly on what is found in the geocoder documentation found at Google Maps Geocoder API

df = pd.DataFrame({'address':address_list,'latitude':locations_latitude,'longitude':locations_longitude, 'formatted_address':formatted_address})

Directions

Google Maps Directions API docs

The Directions API is a service that calculates directions between locations. You can search for directions for several modes of transportation, including transit, driving, walking, or cycling.

origin=(-28.5588,29.77523)
destination = (-29.595413,30.3799223)
waypoints = [(-29.778758,31.043515),(-28.757862,31.902001),(-27.769209,30.79068899999999),(-30.154131,30.058675)]

import gmaps
from datetime import datetime
now = datetime.now()

#configure api
gmaps.configure(api_key=apikey)

#Create the map
fig = gmaps.figure()
#create the layer
layer = gmaps.directions.Directions(origin, destination,waypoints = waypoints,optimize_waypoints=True,
                                    mode='car',api_key=apikey,departure_time = now)
#Add the layer
fig.add_layer(layer)
fig

origin_dir='-28.5588,29.77523'
destination_dir = '-29.595413,30.3799223'
waypoints_dir = ['-29.778758,31.043515|-28.757862,31.902001|-27.769209,30.79068899999999|-30.154131,30.058675']

from datetime import datetime
now = datetime.now()
import googlemaps

#### Setting u the API key to connect to Google maps API

#Perform request to use the Google Maps API web service
gmaps = googlemaps.Client(key=apikey)

for i in waypoints_dir:
     directions = gmaps.directions(origin = origin_dir,waypoints = i,destination = destination_dir,
                                  mode='driving',optimize_waypoints=True,departure_time = now)

start_address = []
end_address = []
distance = []
journey_time = []

for i in range(0, (len(df)-1)):
    distance.append(directions[0]['legs'][i]['distance']['text'])
    journey_time.append(directions[0]['legs'][i]['duration']['text'])
    start_address.append(directions[0]['legs'][i]['start_address'])
    end_address.append(directions[0]['legs'][i]['end_address'])

 df_distance = pd.DataFrame({'start_address':start_address,'end_address':end_address,
                            'distance':distance,'journey_time':journey_time},
                            columns = ['start_address','end_address','distance','journey_time'])
                       
 ### Total distance travelled

 total_distance = 0
 for i in range(0, len(df)-1):
     total_distance += float(df_distance['distance'][i][:-3])

 print('Total distance travelled = {} km'.format(total_distance))

 ### Find journey time

 import numpy as np

 total_journey_time_hrs = 0
 total_journey_time_mins = 0
 for i in range(0, len(df)-1):
     total_journey_time_hrs += np.int(df_distance['journey_time'][i][0])

total_journey_time_hrs = total_journey_time_hrs + total_journey_time_mins//60

total_journey_time_mins = total_journey_time_mins%60

print('The total journey time is: {} hours and {} minutes'.format(total_journey_time_hrs,
                                                             total_journey_time_mins))

Articles consulted for hints

Using gmplot package
[How to use the Google Maps Distance-Matrix API](https://medium.com/how-to-use-google-distance-matrix-api-in-python/how-to-use-google distance-matrix-api-in-python-ef9cd895303c)
How to plot route using Python and Google Maps API
Google Maps in Python

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