選擇特定<tr>標籤與BeautifulSoup

Question

我的讀取與BeautifulSoup一些HTML錶行這段代碼：

from bs4 import BeautifulSoup 
import urllib2 
import re 

page = urllib2.urlopen('www.something.bla') 
soup = BeautifulSoup(page) 
rows = soup.findAll('tr', attrs={'class': re.compile('class1.*')}) 

這是我得到的結果：

<tr class="class1 class2 class3">...</tr> 
<tr class="class1 class2 class3">...</tr> 
<tr class="class1 class5">...</tr> 
<tr class="class1_a class5_a">...</tr> 
<tr class="class1 class5">...</tr> 
<tr class="class1_a class5_a">...</tr> 
<!-- etc. --> 

然而，我'想排除（或不首先選擇它們）那些具有class1 class2 class3作爲屬性的行。

我該怎麼做？
感謝您的幫助！

Answer 1

也許沒有正則表達式更容易。這適用於BeautifulSoup 3：

from BeautifulSoup import BeautifulSoup 

page = """ 
<tr class="class1 class2 class3">1</tr> 
<tr class="class1 class2 class3">2</tr> 
<tr class="class1 class5">3</tr> 
<tr class="class1_a class5_a">4</tr> 
<tr class="class1 class5">5</tr> 
<tr class="class1_a class5_a">6</tr> 
<tr>7</tr>""" 

def cond(x): 
    if x: 
     return x.startswith("class1") and not "class2 class3" in x 
    else: 
     return False 

soup = BeautifulSoup(page) 
rows = soup.findAll('tr', {'class': cond}) 

for row in rows: 
    print row 

=>

<tr class="class1 class5">3</tr> 
<tr class="class1_a class5_a">4</tr> 
<tr class="class1 class5">5</tr> 
<tr class="class1_a class5_a">6</tr> 

---

隨着BeautifulSoup 4，我能使其工作如下：

import re 
from bs4 import BeautifulSoup 

page = """ 
<tr class="class1 class2 class3">1</tr> 
<tr class="class1 class2 class3">2</tr> 
<tr class="class1 class5">3</tr> 
<tr class="class1_a class5_a">4</tr> 
<tr class="class1 class5">5</tr> 
<tr class="class1_a class5_a">6</tr> 
<tr>7</tr>""" 

soup = BeautifulSoup(page) 
rows = soup.find_all('tr', {'class': re.compile('class1.*')}) 

for row in rows: 
    cls = row.attrs.get("class") 
    if not ("class2" in cls or "class3" in cls): 
     print row 

=>

<tr class="class1 class5">3</tr> 
<tr class="class1_a class5_a">4</tr> 
<tr class="class1 class5">5</tr> 
<tr class="class1_a class5_a">6</tr> 

在BS4中，像class這樣的多值屬性具有字符串列表作爲它們的值，而不是字符串。見http://www.crummy.com/software/BeautifulSoup/bs4/doc/#id12。