Python Weather Forecast Wallpaper

This code downloads yahoo xml weather forecast data and draws it on north east side of a picture
you can create a script like this

#!/bin/bash
sleep 25 && /home/hide1713/python_project/get_weather.py -c -i
/home/hide1713/Pictures/lamp.jpg -z 47408

then use chmod +x to make it executable, add this script in your start session.

It will create a new picture “pciture_name_new”, use this picture as your wallpaper.
NOTE: This script need lxml packet.

#!/usr/bin/env python
"""
Weather Forecast to wallpaper
By Lei Chen (hide1713 at gmail dot com)
This program reads xml data from yahoo then uses convert command to write a string on wallpaper
"""
from lxml import etree
import urllib2,os,getopt,sys
picture_name=''
zipcode=''
f_or_c='c'
args=sys.argv[1:]
def usage ():
    """"""
    print """Weather Forecast Wallpaper:
Usage:
-i <wallpaper file name>
-[f|c] : Fahrenheit/Celius
-z     : Your zipcode
"""

try:
    opts,args=getopt.getopt(args,'z:fci:')
except getopt.GetoptError, err:
    # print help information and exit:
    print str(err) # will print something like "option -a not recognized"
    usage()
    sys.exit(2)
for o,a in opts:
    if o=="-c":
       f_or_c='c'
    if o=='-f':
       f_or_c='f'
    if o=="-i":
       picture_name=a
    if o=='-z':
        try:
            zipcode=int(a)
        except:
            print "zip code must be a number"
            sys.exit(2)

if not os.access(picture_name,os.W_OK):
   print "Can not write picture"
   usage()
   sys.exit(1)

if zipcode=='':
   print "No zipcode?"
   sys.exit(1)

print "Generating ",zipcode," weather forecast to ",picture_name
req=urllib2.Request("http://weather.yahooapis.com/forecastrss?p=%d&u=%s"%(zipcode,f_or_c))
fd = urllib2.urlopen(req)

tree=etree.fromstring(fd.read(),base_url="http://weather.yahooapis.com/forecastrss?p=47408")
s=''
for ele in tree.iter():
    if ele.tag=='{http://xml.weather.yahoo.com/ns/rss/1.0}forecast':
        s+=ele.attrib['day']+" "+ele.attrib['low']+"-"+ele.attrib['high']
        s+=" "+ele.attrib['text']+" "
os.popen("""convert %s  -pointsize 24 -draw "gravity NorthEast fill white text 0,12'%s'" %s"""%(picture_name,s,picture_name[:-4]+"_new"+picture_name[-4:]))