import ConfigParser, sys, json

from operator import itemgetter

import iso3166, geopy, requests, csv

from geopy import distance

import cache

config = ConfigParser.ConfigParser()

config.read("settings.cfg")

geonames_username = config.get("geonames","username")

print "Talking to Geonames as "+geonames_username

GEONAMES_API_URL = "http://api.geonames.org/searchJSON"

print "Finding largest cities in country:"

alpha3_to_city = {}

for country in iso3166.countries:

print " "+country.name

cache_key = country.alpha3+"-geocode"

results_text = None

if cache.contains(cache_key):

results_text = cache.get(cache_key)

else:

response = requests.get(GEONAMES_API_URL,

params={ 'country':country.alpha2,

'q':country.name.split(",")[0],

'username':geonames_username})

results_text = response.content

cache.put(cache_key,results_text)

results = json.loads(results_text)

try:

cities = sorted([place for place in results['geonames'] if "PPL" in place['fcode']], key=itemgetter('population'),reverse=True)

except KeyError:

print "Error! Couldn't find an fcodes"

continue

if len(cities)>0:

print " biggest city = "+cities[0]['name']

alpha3_to_city[country.alpha3] = cities[0]

else:

print "Error! No cities found!"

print "Computing Distances"

distances = {}

for alpha31,city1 in alpha3_to_city.iteritems():

distances[alpha31] = {}

for alpha32,city2 in alpha3_to_city.iteritems():

try:

distances[alpha31][alpha32] = distance.distance(

(city1['lat'],city1['lng']),(city2['lat'],city2['lng'])

).kilometers

except ValueError:

print " Could not compute distance between "+alpha31+" and "+alpha32

distances[alpha31][alpha32] = "?"

print "Outputting"

csvfile = open('distances.csv', 'wb')

csvwriter = csv.writer(csvfile)

headers = [' '] + sorted(alpha3_to_city.keys())

csvwriter.writerow(headers)

for alpha31 in sorted(alpha3_to_city.keys()):

row = [alpha31]

print " "+alpha31

for alpha32 in headers[1:]:

row.append( distances[alpha31][alpha32] )

csvwriter.writerow(row)

print "Done"