get the pm2.5 of special city

pm25.py

#!/usr/bin/env python
#-*- coding:utf-8 -*-

import urllib
import sys
import re

def pager(city, fmt='utf-8'):
    url  = 'http://www.chapm25.com/city/{0}.html'.format(city)
    page = urllib.urlopen(url).read()
    return page.decode(fmt, 'ignore')

def parser(page, regex):
    return regex.findall(page)

def pm25(city):
    page  = pager(city)
    regex = re.compile(r'<div\s+class="span8\s+pmtips">.*?cityid=.*?>(?P<pm>.+?)[ <].*?\((.*?)\)', re.DOTALL)
    try:
        p = parser(page, regex)[0]
        pm = p[0]
        sort = p[1]
        print '%-10s %-5s%-30s' % (city, pm, sort)
    except IndexError:
        print 'no pm2.5 data of such city'

if len(sys.argv) > 1:
    city = sys.argv[1]
else:
    city = 'chengdu'
pm25(city)

chengdu    172  排名 130/190                                     
shanghai   127  排名 64/190                     
beijing    518  排名 187/190 
hanzhou    518  排名 187/190
guangzhou  156  排名 87/190