Get a list of Wikipedia articles near a location

wikby.py

#!/usr/bin/env python

import sys, re, urllib
from decimal import Decimal as dec

def error(message):
   print message
   sys.exit(1)

def parse_lat_lon_string(lat_lon):
   lat, lon = lat_lon.split(',', 1)
   lat, lon = lat.strip(), lon.strip()
   lat, lon = dec(lat), dec(lon)

   if not (dec(-90) <= lat <= dec(90)):
      raise ValueError("Latitude not within -90 to 90 inclusive")
   if not (dec(-180) <= lon <= dec(180)):
      raise ValueError("Longitude not within -180 to 180 inclusive")

   return lat, lon

r_string = re.compile(r'("(\\.|[^"\\])*")')
r_json = re.compile(r'^[,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]+$')
env = {'__builtins__': None, 'null': None, 'true': True, 'false': False}

def json(text): 
   """Evaluate JSON text safely (we hope)."""
   if r_json.match(r_string.sub('', text)): 
      text = r_string.sub(lambda m: 'u' + m.group(1), text)
      return eval(text.strip(' \t\r\n'), env, {})
   raise ValueError('Input must be serialised JSON.')

def distance(d):
   if d.endswith("m"):
      try: dist = float(d[:-1])
      except: return d
      if dist > 99:
         return str(round(dist / 1000, 1)) + "km"
   return d

def wikilocation(lat_lon, locale="en"):
   try: lat, lon = parse_lat_lon_string(lat_lon)
   except Exception, e:
      error("Couldn't parse lat,lon input. Python says: %s" % e)

   data = {
      "locale": locale,
      "lat": lat,
      "lng": lon,
      "radius": 20000,
      "limit": 36
   }

   query = urllib.urlencode(data)
   service = "http://api.wikilocation.org/articles"
   u = urllib.urlopen("?".join((service, query)))
   bytes = u.read()
   u.close()

   # articles = json.loads(bytes)
   articles = json(bytes)
   results = []
   seen = set()

   for article in articles["articles"]:
      result = article["title"] + " ("  + distance(article["distance"]) + ")"
      seen_result = article["title"].strip("0123456789- ")
      if not (seen_result in seen):
         results.append(result)
         seen.add(seen_result)

   response = ""
   while (len(response) < 360) and results:
      response += results[0] + ", "
      results = results[1:]
   return response.rstrip(", ")

def wikby(args):
   if args.startswith(":"):
      locale, lat_lon = args.split(" ", 1)
      locale = locale.lstrip(":")
   else: locale, lat_lon = "en", args
   print wikilocation(lat_lon, locale=locale)

# e.g. wikby("51.500688, -0.124411")