geonames parsing + indexing

import collections
import json

class GeoName(collections.namedtuple('GeoName',
                                     ['country_code',
                                      'postal_code',
                                      'place_name',
                                      'admin_name_1', 'admin_code_1',
                                      'admin_name_2', 'admin_code_2',
                                      'admin_name_3', 'admin_code_3',
                                      'latitude', 'longitude',
                                      'accuracy'])):
    pass

def tile((lat, lng)):
    return int(lat * 10), int(lng * 10)

def box((x, y), w=1):
    for i in xrange(-w, w + 1):
        for j in xrange(-w, w + 1):
            yield x + i, y + j

def dist(A, B):
    return sum((a - b) ** 2 for a, b in zip(A, B))

def parse(filename='allCountries.txt'):
    with open(filename) as handle:
        for line in handle:
            g = GeoName(*line.strip('\n').split('\t'))
            if g.place_name and g.latitude and g.longitude:
                yield (float(g.latitude), float(g.longitude)), g.place_name

def index(geonames):
    for latlng, place in geonames:
        yield '%s,%s' % tile(latlng), json.dumps([latlng, place])

def fetch(point, db):
    for val in db.get('%s,%s' % point, ()):
        yield json.loads(val)

def query(latlng, db):
    return sorted((dist(cell[0], latlng), cell)
                  for point in box(tile(latlng))
                  for cell in fetch(point, db))