A Script to Calculate the nearest establishments to a given postcode and distance

geoserve.py

import math

EARTH_DIAMETER = 2 * 6378.2
PI = 3.14159265
RAD_CONVERT = PI / 180.0

postcodes = open('geoserve_postcodes.csv', 'r')

given_postcode = 'CB24 6AJ'
given_distance = 3000.0 # The distance is given in metres
my_location = None
data = None


class Postcode:
    def __init__(self,  line):
        data = line.split(',')
        self.postcode = data[0]
        self.east = data[1]
        self.north = data[2]
        self.latitude = data[3]
        self.longitude = data[4].strip('\n')

    def calc_distance(self, loc):

        lat1 = self.latitude
        lon1 = self.longitude
        lat2 = loc.latitude
        lon2 = loc.longitude

        # convert degrees to radians
        lat1 = (float(lat1) * RAD_CONVERT)
        lat2 = (float(lat2) * RAD_CONVERT)

        # find the deltas
        delta_lat = lat2 - lat1
        delta_lon = (float(lon2) - float(lon1)) * RAD_CONVERT

        # Find the great circle distance in km
        temp = pow(math.sin(delta_lat/2),2) + math.cos(lat1) * math.cos(lat2) * pow(math.sin(delta_lon/2),2)
        return EARTH_DIAMETER * math.atan2(math.sqrt(temp),math.sqrt(1-temp))


# Create a Postcode object from the given_postcode
for location in postcodes:
    info = location.split(',')
    if given_postcode == info[0]:
        my_location = Postcode(location)
        postcodes.close()
        break


# Get the name of the pub/s for a given postcode
def get_pub(postcode):
    return_list = []
    with open('geoserve_pubs.csv', 'r') as p:
        for lines in p:
            if postcode in lines:
                info = lines.split(',')
                return_list.append(info[0].strip('\n'))
        return return_list
        

if postcodes.closed:
    with open('geoserve_postcodes.csv', 'r') as postcodes:
        for line in postcodes:
            data = Postcode(line)
            distance_km = my_location.calc_distance(data)
            distance_m = distance_km*1000

            if round(distance_m) < given_distance:
                pub_name = get_pub(data.postcode)
                if pub_name:
                    print str(pub_name) + ' - ' + str(distance_m)

postcodes.close()