Finding zip codes within the radius of a given address using SimpleGeo

simplegeo_zips.py

from math import pi,sqrt,sin,cos,asin,atan2
from simplegeo import Client
import json

def get_nearby_zips(address, radius, client):
	'''
	Given an address and radius (and the SimpleGeo client), returns
	a comma-separated list of zip codes within that radius.
	'''
	context = client.context.get_context_by_address(address)
	lat = float(context['query']['latitude'])
	lon = float(context['query']['longitude'])

	# Convert the initial lat, lon to radians

	lat = lat * pi / 180
	lon = lon * pi / 180

	earths_radius = 6372.8

	# Find the hypotenuse of the triangle and convert to kilometers
	distance = sqrt(2 * radius**2)
	distance = distance * 1.609344

	ne_bearing = 45 * pi / 180
	sw_bearing = 225 * pi / 180

	# Get the Southwest Lat/Lon in degrees

	swLatRad = asin(sin(lat) * cos(distance/earths_radius) + 
			cos(lat) * sin(distance/earths_radius) * cos(ne_bearing))
	swLat = swLatRad * 180 / pi

	swLonRad = lon + atan2(sin(ne_bearing) * sin(distance/earths_radius) *
			cos(lat), cos(distance/earths_radius) - sin(lat) * sin(swLatRad))
	swLon = swLonRad * 180 / pi

	# Get the Northeast Lat/Lon in degrees

	neLatRad = asin (sin(lat) * cos(distance/earths_radius) + 
			cos(lat) * sin(distance/earths_radius) * cos(sw_bearing))
	neLat = neLatRad * 180 / pi

	neLonRad = lon + atan2(sin(sw_bearing) * sin(distance/earths_radius) *
			cos(lat), cos(distance/earths_radius) - sin(lat) * sin(neLatRad))
	neLon = neLonRad * 180 / pi

	# Find the zip codes within the given mile radius
	# and put them in a comma-separated string

	bbox_ZIPs = client.context.get_context_from_bbox(swLat, swLon, neLat, neLon,
												features__category='Postal Code')
	zips = sorted(bbox_ZIPs['features'],cmp=lambda x,y: cmp(x['name'],y['name']))
	zips = ",".join(zip['name'] for zip in zips)

	return zips


# Instantiate the SimpleGeo Client
client = Client('KEY', 'SECRET')

address = "1000 Commerce Park Dr, Williamsport PA"
radius = 30

zips = get_nearby_zips(address, radius, client)
print(zips)