beautifulsoup：find_all上bs4.element.ResultSet对象或列表？ [英] beautifulsoup: find_all on bs4.element.ResultSet object or list?

问题描述

您好，我将find_all应用于 beautifulsoup对象，并找到一些 bs4.element.ResultSet对象或者 list 。

我想在那里进一步做find_all，但是它不允许在 bs4.element.ResultSet对象。我可以遍历 bs4.element.ResultSet对象的每个元素来执行find_all。但是，我可以避免循环，只是将其转换回美丽的对象？

请参阅详细代码。谢谢

  html_1 =
< table> 
< thead> 
 < tr class =myClass> 
< th> 
< th> 
< th> 
 $ D 
 
 $ lt; / thead 
< / table> 

汤= BeautifulSoup（html_1，'html.parser'）
 
类型（汤）＃bs4.BeautifulSoup 
 
＃在findsall对象
 th_all = soup上做find_all。 find_all（'th'）
 
＃结果是类型bs4.element.ResultSet或类似列表
类型（th_all）＃bs4.element.ResultSet 
类型（th_all [ 0：1]）#list 
 
＃现在我想进一步做find_all 
 th_all.find_all（text ='A'）＃不工作
 
＃can我避免了这种循环的需要？ 
 for th_all：
 th.find_all（text ='A'）#works 
  

解决方案

ResultSet class是一个列表的子类，而不是 Tag class ，其中 find * 定义的方法。循环访问 find_all（）是最常见的方法：

  th_all = soup.find_all（'th'）
 result = [] 
 for th_all：
 result.extend（th.find_all（text ='A'））
  

通常， CSS选择器可以帮助您一次解决它，除非您可以使用 find_all（）可以通过 select（）方法来实现。例如，在 bs4 CSS选择器中没有文本搜索。但是，例如，如果您必须在 th 元素中找到所有元素，例如 b 元素，则可以执行：

  soup.select（th td）
  

Hi so I apply find_all on a beautifulsoup object, and find something, which is an bs4.element.ResultSet object or a list.

I want to further do find_all in there, but it's not allowed on a bs4.element.ResultSet object. I can loop through each element of the bs4.element.ResultSet object to do find_all. But can I avoid looping and just convert it back to a beautifulsoup object?

See code for details please. Thanks

html_1 = """
<table>
    <thead>
        <tr class="myClass">
            <th>A</th>
            <th>B</th>
            <th>C</th>
            <th>D</th>
        </tr>
    </thead>
</table>
"""
soup = BeautifulSoup(html_1, 'html.parser')

type(soup) #bs4.BeautifulSoup

# do find_all on beautifulsoup object
th_all = soup.find_all('th')

# the result is of type bs4.element.ResultSet or similarly list
type(th_all) #bs4.element.ResultSet
type(th_all[0:1]) #list

# now I want to further do find_all
th_all.find_all(text='A') #not work

# can I avoid this need of loop?
for th in th_all:
    th.find_all(text='A') #works

解决方案

ResultSet class is a subclass of a list and not a Tag class which has the find* methods defined. Looping through the results of find_all() is the most common approach:

th_all = soup.find_all('th')
result = []
for th in th_all:
    result.extend(th.find_all(text='A'))

Usually, CSS selectors may help you solve it in one go except that not everything you can do with find_all() is possible with the select() method. For instance, there is no "text" search available in bs4 CSS selectors. But, if, for example, you had to find all, say, b elements inside th elements, you could do:

soup.select("th td")

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