爬取提取旧金山天气页面的信息
#导入需要的包和模块，这里需要的是 urllib.request 和 Beautifulsoup
import urllib.request as urlrequest
from bs4 import BeautifulSoup
#通过urllib来获取我们需要爬取的网页
weather_url='http://forecast.weather.gov/MapClick.php?lat=37.77492773500046&lon=-122.41941932299972'
page_content=urlrequest.urlopen(weather_url).read()
#用 BeautifulSoup 来解析和获取我们想要的内容块
soup=BeautifulSoup(page_content,'html.parser')
soup_forecast=soup.find(id='seven-day-forecast-container')
#找到我们想要的那一部分内容
date_list=soup_forecast.find_all(class_='period-name')
desc_list=soup_forecast.find_all(class_='short-desc')
temp_list=soup_forecast.find_all(class_='temp')
#将获取的内容更好地展示出来，用for循环来实现
for i in range(9):
date=date_list[i].get_text()
desc=desc_list[i].get_text()
temp=temp_list[i].get_text()
print("{} - {} - {}".format(date,desc,temp))
输出结果如下：
Tonight - Slight ChanceRain - Low: 48 °F
Wednesday - Patchy Fogthen Sunny - High: 58 °F
WednesdayNight - Mostly Clearthen PatchyFog - Low: 46 °F
Thursday - Patchy Fogthen MostlyCloudy - High: 59 °F
ThursdayNight - Patchy Fog - Low: 48 °F
Friday - Patchy Fogthen MostlyCloudy - High: 60 °F
FridayNight - Slight ChanceRain andPatchy Fog - Low: 52 °F
Saturday - Chance Rainand PatchyFog - High: 60 °F
SaturdayNight - Chance Rain - Low: 52 °F
