random_points_in_india.py

import csv
import random
from datetime import datetime
from osgeo import ogr
from shapely.geometry import Point
from shapely.prepared import prep
from shapely.wkb import loads

start_time = all_start_time = datetime.now()
g = ogr.Open('world.shp') # Open the shapefile with all the world's countries
# Loop over the different features until we find INDIA
for feat in g.GetLayer(0):
    if feat.GetFieldAsString('NAME').find('INDIA') >= 0:
        break # We found India, break out of the loop
              # feat now holds the feature of INDIA
# Get the geometry of India
India = loads(feat.GetGeometryRef().ExportToWkb())
IndiaP = prep(India)
print 'reading/searching shapefile:', datetime.now() - start_time
start_time = datetime.now()
lon_min, lat_min, lon_max, lat_max = India.bounds # Now get the envelope

n_points = 0 # A counter
india_lonlat = [] # A list where we'll store longitudes/latitudes within India
while n_points < 10000: # Until we reach our required number of points...
    # Draw random longitudes and latitudes within the envelope
    r_lon = random.uniform(lon_min, lon_max)
    r_lat = random.uniform(lat_min, lat_max)
    pt = Point(r_lon, r_lat)
    # Is this geometry within India?
    if IndiaP.contains(pt):
        # yes! Store the latitude&longitude and update counter
        india_lonlat.append([r_lon, r_lat])
        n_points += 1
print 'generated', n_points, 'points:', datetime.now() - start_time
start_time = datetime.now()
# Save to a CSV file
fp = open('india.csv', 'wb')
w = csv.writer(fp)
w.writerow(['Longitude', 'Latitude'])# Header
w.writerows(india_lonlat)
fp.close()
print 'wrote CSV file:', datetime.now() - start_time
start_time = datetime.now()
print 'total time:', datetime.now() - all_start_time