：与ELIF声明

Question

“IndexError列表索引超出范围”我写了解析来自某些网站的HTML代码提取特定数据的脚本。我有两个不同的网站，我从中提取这些数据，所以我使用了elif语句。以下是代码：

import urllib 

class city : 
    def __init__(self, city_name, link) : 
      self.name = city_name 
      self.url = link 
      self.high0 = 0 
      self.high1 = 0 
      self.high2 = 0 
      self.high3 = 0 
      self.high4 = 0 
      self.high5 = 0 
      self.high6 = 0 
      self.low0 = 0 
      self.low1 = 0 
      self.low2 = 0 
      self.low3 = 0 
      self.low4 = 0 
      self.low5 = 0 

    def retrieveTemps(self) : 
      filehandle = urllib.urlopen(self.url) 

      # get lines from result into array 
      lines = filehandle.readlines() 

      # (for each) loop through each line in lines 
      line_number = 0 # a counter for line number 
      for line in lines: 
        line_number = line_number + 1 # increment counter 

# find string, position otherwise position is -1 

        position1 = line.rfind('#f2') 
        if position1 > 0 : 
          self.high0 = lines[line_number].split('&')[0].split('>')[1] # next line: high 
          self.low0 = lines[line_number + 10].split('&')[0].split('>')[1] # next line:low 
        elif position1 < 0 : 
          position1 = line.rfind('>Overnight') 
          if position1 > 0 : 
            self.high0 = lines[line_number + 9].split('&')[0].split(':')[1] # next line: high 
            self.low0 = lines[line_number + 15].split('&')[0].split(':')[1] # next line:low 

当position1 = line.rfind（'＃f2'）时，该脚本完美工作。然而，当它不能找到“＃F2”（这仅位于第一个站点，而不是第二的HTML代码），我想告诉它来寻找“>一夜之间”，然后提取的数据'：'和'&'。 '数据'将始终是一个单一的数字。我在考虑一个问题，可能是这个数字的两边有一个空格，我试图提取，但我不知道如何解决这个问题。当我运行该脚本我得到错误：

self.high0 =行[LINE_NUMBER + 9] .split（ '& '）[0] .split（'：'）[1]＃下一行：高 “IndexError：列表索引超出范围”

作为参考，下面是HTML代码我解析用于第一网站：

</h3><img src="/weathericons/15.gif" longdesc="#f2" alt="Rain mixed with snow" title="Rain mixed with snow" /><ul> 
       <li class="high" title="High">3&deg;C</li> 
       <li class="low">&nbsp;</li> 
       <li class="pop">&nbsp;</li> 
      </ul> 
      </div> 

和从第二网站（一个针对我收到错误）：

<p class="txt-ctr-caps">Overnight<br><br></p> 
      <p><img src="/images/wtf/medium/nra60.png" width="86" height="86" alt="Rain Likely Chance for Measurable Precipitation 60%" title="Rain Likely Chance for Measurable Precipitation 60%" /></p> 
     <p>Rain<br>Likely<br></p> 
      <p class="point-forecast-icons-low">Low: 3 &deg;C</p> 
    </div> 
    <div class="one-ninth-first"> 
      <p class="txt-ctr-caps">Thursday<br><br></p> 
      <p><img src="/images/wtf/medium/ra70.png" width="86" height="86" alt="Rain Likely Chance for Measurable Precipitation 70%" title="Rain Likely Chance for Measurable Precipitation 70%" /></p> 
     <p>Rain<br>Likely<br></p> 
      <p class="point-forecast-icons-high">High: 9 &deg;C</p> 
    </div> 

任何帮助将不胜感激，谢谢！

Answer 1

现在你已经提供了完整代码： 试试这

def retrieveTemps(self) : 
     filehandle = urllib.urlopen(self.url) 
     lines = filehandle.read() # modified 

     position1 = lines.rfind('#f2') 
     if position1 > 0 : 
       self.high0 = lines[position1:].split('&')[0].split('>')[1] # next line: high 
       self.low0 = lines[position1+10:].split('&')[0].split('>')[1] # next line:low 
     elif position1 < 0 : 
       position1 = lines.rfind('>Overnight') 
       if position1 > 0 : 
         self.high0 = lines[position1+9:].split('&')[0].split(':')[1] # next line: high 
         self.low0 = lines[position1+15:].split('&')[0].split(':')[1] # next line:low 

即使是doesn'e帮助试图用基本的打印语句调试代码就像什么都在你的变量，如线和生产线，当你有正在处理。