Python3 XML 获取雅虎天气的实现方法

#!/usr/bin/env python3
# coding: utf-8
import os
from datetime import datetime
from urllib import request 
from xml.parsers.expat import ParserCreate 
file_name = "weather.txt"
for root,dirs,files in os.walk("."):
 if file_name in files:
  os.remove(os.path.join(root,file_name))
def yahoo_weather(data):
 flag = False
 weather = {"city": "","pubdate": "","forecast": []}
 def start_element(name,attrs):
  if name == "yweather:location":
   weather["city"] = weather["city"] + attrs["city"]
   weather["city"] = weather["city"] + " " + attrs["country"]
  if name == "yweather:forecast":
   forecast = {}
   forecast["date"] = attrs["date"]
   forecast["day"] = attrs["day"]
   forecast["high"] = attrs["high"]
   forecast["low"] = attrs["low"]
   forecast["text"] = attrs["text"]
   weather["forecast"].append(forecast)
  if name == "pubDate":
   nonlocal flag
   flag = True
  
 def char_data(text):
  nonlocal flag
  if flag:
   weather["pubdate"] = text
   flag = False
 parser = ParserCreate()
 parser.StartElementHandler = start_element
 parser.CharacterDataHandler = char_data
 parser.Parse(data)
 return weather
def print_weather(weather):
 with open(file_name,"a") as f:
  s = "City: %snPub date: %s" %(weather["city"],weather["pubdate"])
  print("%s" %(weather["city"]))
  f.write(s + "n")
  for forecast in weather["forecast"]:
   date = datetime.strptime(forecast["date"],"%d %b %Y").strftime("%Y-%m-%d")
   s = "Date: %s High: %s Low: %s Weather: %s" %(date,forecast["high"],forecast["low"],forecast["text"])
   f.write(s + "n")
  f.write("n")
citys = ["2151330","2151849","44418","615702","2514815"]
for city in citys:
 url = "https://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20weather.forecast%20where%20woeid%20%3D%20"
 url = url + city
 url = url + "&format=xml"
 with request.urlopen(url,timeout=4) as f:
  weather = yahoo_weather(f.read())
  print_weather(weather)
print("weather conditions has written to %s" %(file_name))