geo-freebase.py

#!/usr/bin/env python

import json
import urllib

def geocode(postal_code):
    """A function for turning a postal code into a geo-coordinate using Freebase."""
    url = "https://www.googleapis.com/freebase/v1/mqlread?query="
    q = {
        "type": "/location/postal_code",
        "/location/postal_code/postal_code": postal_code,
        "/location/location/geolocation": {
            "/location/geocode/latitude": None,
            "/location/geocode/longitude": None
        }
    }
    r = json.loads(urllib.urlopen(url + urllib.quote(json.dumps(q))).read())
    if not r['result']:
        return None
    geo = r['result']['/location/location/geolocation']
    return geo['/location/geocode/latitude'], geo['/location/geocode/longitude']

# but not all postal codes are in freebase, try BN1 9QR
for postal_code in ["20901", "BN1 9RH"]:
    print postal_code, ": ", geocode(postal_code)