import urllib,urllib2,time
addr_file = 'addresses.csv'
out_file  = 'addresses_geocoded.csv'
out_file_failed = 'failed.csv'
sleep_time = 2
root_url = "http://maps.google.com/maps/geo?"
gkey = "YourGoogleKeyGoesHere"
return_codes = {'200':'SUCCESS',
				'400':'BAD REQUEST',
				'500':'SERVER ERROR',
				'601':'MISSING QUERY',
				'602':'UNKOWN ADDRESS',
				'603':'UNAVAILABLE ADDRESS',
				'604':'UNKOWN DIRECTIONS',
				'610':'BAD KEY',
				'620':'TOO MANY QUERIES'
				}
def geocode(addr,out_fmt='csv'):
	#encode our dictionary of url parameters
	values = {'q' : addr, 'output':out_fmt, 'key':gkey}
	data = urllib.urlencode(values)
	#set up our request
	url = root_url+data
	req = urllib2.Request(url)
	#make request and read response
	response = urllib2.urlopen(req)
	geodat = response.read().split(',')
	response.close()
	#handle the data returned from google
	code = return_codes[geodat[0]]
	if code == 'SUCCESS':
		code,precision,lat,lng = geodat
		return {'code':code,'precision':precision,'lat':lat,'lng':lng}
	else:
		return {'code':code}
def main():
	#open our i/o files
	outf = open(out_file,'w')
	outf_failed = open(out_file_failed,'w')
	inf = open(addr_file,'r')
	for address in inf:
		#get latitude and longitude of address
		data = geocode(address)
		#output results and log to file
		if len(data)>1:
			print "Latitude and Longitude of "+address+":"
			print "\tLatitude:",data['lat']
			print "\tLongitude:",data['lng']
			outf.write(address.strip()+data['lat']+','+data['lng']+'\n')
			outf.flush()
		else:
			print "Geocoding of '"+addr+"' failed with error code "+data['code']
			outf_failed.write(address)
			outf_failed.flush()
		#play nice and don't just pound the server with requests
		time.sleep(sleep_time)
	#clean up
	inf.close()
	outf.close()
	outf_failed.close()
if __name__ == "__main__":
	main()

http://canadianamp.ca/2008/12/05/simple-geocoding-with-python-and-urllib/

Python: geocode address via urllib

python

Python