美丽的汤抛出`IndexError`答案

【问题标题】：Beautiful Soup throws `IndexError`美丽的汤抛出`IndexError`
【发布时间】：2013-09-30 03:34:52
【问题描述】：

我正在使用 Python 2.7 和 Beautiful Soup 3.2 抓取网站。我对这两种语言都很陌生，但是从文档中我开始了一些。

我现在所做的和拥有的（失败的部分）：

# Import the classes that are needed
import urllib2
from BeautifulSoup import BeautifulSoup

# URL to scrape and open it with the urllib2
url = 'http://www.wiziwig.tv/competition.php?competitionid=92&part=sports&discipline=football'
source = urllib2.urlopen(url)

# Turn the saced source into a BeautifulSoup object
soup = BeautifulSoup(source)

# From the source HTML page, search and store all <td class="home">..</td> and it's content
hometeamsTd = soup.findAll('td', { "class" : "home" })
# Loop through the tag and store only the needed information, being the home team
hometeams = [tag.contents[1] for tag in hometeamsTd]

# From the source HTML page, search and store all <td class="home">..</td> and it's content
awayteamsTd = soup.findAll('td', { "class" : "away" })
# Loop through the tag and store only the needed information, being the away team
awayteams = [tag.contents[1] for tag in awayteamsTd]

hometeamsTd 的 tag.contents 的内容如下所示：

[
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'Harkemase Boys', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-6077" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'RKC Waalwijk', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-427" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'Dutch KNVB Beker', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-6758" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'PSV', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-3" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'Ajax', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-2" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'Dutch KNVB Beker', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-6758" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'SC Heerenveen', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-14" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'Feyenoord', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-9" />],
    [<img class="flag" src="/gfx/flags/nl.gif" alt="nl" />, u'Dutch KNVB Beker', <img src="/gfx/favourite_off.gif" alt="fav icon" class="fav off" id="team-6758" />]
]

awayteamsTd 的tag.contents 的内容如下所示：

[
    [u'Away-team'], 
    [<img src="/gfx/favourite_off.gif" class="fav off" alt="fav icon" id="team-13" />, u'NEC', <img class="flag" src="/gfx/flags/nl.gif" alt="nl" />], 
    [<img src="/gfx/favourite_off.gif" class="fav off" alt="fav icon" id="team-11" />, u'Heracles', <img class="flag" src="/gfx/flags/nl.gif" alt="nl" />], 
    [<img src="/gfx/favourite_off.gif" class="fav off" alt="fav icon" id="team-428" />, u'Stormvogels Telstar', <img class="flag" src="/gfx/flags/nl.gif" alt="nl" />], 
    [<img src="/gfx/favourite_off.gif" class="fav off" alt="fav icon" id="team-419" />, u'FC Volendam', <img class="flag" src="/gfx/flags/nl.gif" alt="nl" />],
    [<img src="/gfx/favourite_off.gif" class="fav off" alt="fav icon" id="team-7" />, u'FC Twente', <img class="flag" src="/gfx/flags/nl.gif" alt="nl" />],
    [<img src="/gfx/favourite_off.gif" class="fav off" alt="fav icon" id="team-415" />, u'FC Dordrecht', <img class="flag" src="/gfx/flags/nl.gif" alt="nl" />]
]

我试图解决但还没有完全解决的问题是：

代码awayteams = [tag.contents[1] for tag in awayteamsTd] 出现错误：IndexError: list index out of range。这当然是正确的，因为您可以在 awayteamsTd 的 tag.contents 的输出中看到，有一个第一个条目 [u'Away-team']。这就是它失败的原因。但是我怎样才能删除/跳过这个？
在 hometeams 输出中一切正常，但我想排除出现 Dutch KNVB Beker 文本的那些

【问题讨论】：

标签： python beautifulsoup

【解决方案1】：

问题在于“away”单元格（列名）位于带有“away”类的 td 内：

<thead class="title">
    ...
    <tr class="sub">
      ...  
      <td>Home-team</td>
      <td></td>
      <td class="away">Away-team</td>
      <td class="broadcast">Broadcast</td>
    </tr>
  </thead>
</thead>

使用切片跳过它：

awayteamsTd = soup.findAll('td', { "class" : "away" })[1:]

另外，如果您想从主队列表中排除 Dutch KNVB Beker，请在列表推导表达式中添加一个条件：

hometeams = [tag.contents[1] for tag in hometeamsTd if tag.contents[1] != 'Dutch KNVB Beker']

【讨论】：

【解决方案2】：

awayteams = []
for tag in awayteamsTd:
    if len(tag.contents) > 1:
        awayteams.append(tag.contents[1])

【讨论】：