Python 使用 BeautifulSoup 提取特定的 TD 表格元素文本？
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Using BeautifulSoup To Extract Specific TD Table Elements Text?
提问by Pike Man
I trying to extract IP Addresses from a autogenerated HTML table using the BeautifulSoup library and im having a little trouble.
我尝试使用 BeautifulSoup 库从自动生成的 HTML 表中提取 IP 地址，但遇到了一些麻烦。
The HTML is structured like so:
HTML 的结构如下：
<html>
<body>
<table class="mainTable">
<thead>
<tr>
<th>IP</th>
<th>Country</th>
</tr>
</thead>
<tbody>
<tr>
<td><a href="hello.html">127.0.0.1<a></td>
<td><img src="uk.gif" /><a href="uk.com">uk</a></td>
</tr>
<tr>
<td><a href="hello.html">192.168.0.1<a></td>
<td><img src="uk.gif" /><a href="us.com">us</a></td>
</tr>
<tr>
<td><a href="hello.html">255.255.255.0<a></td>
<td><img src="uk.gif" /><a href="br.com">br</a></td>
</tr>
</tbody>
</table>
The small code below extracts the text from the two td rows but i only need the IP data, not the IP and Country data:
下面的小代码从两个 td 行中提取文本，但我只需要 IP 数据，而不需要 IP 和国家/地区数据：
from bs4 import BeautifulSoup
soup = BeautifulSoup(open("data.htm"))
table = soup.find('table', {'class': 'mainTable'})
for row in table.findAll("a"):
print(row.text)
this outputs:
这输出：
127.0.0.1
uk
192.168.0.1
us
255.255.255.0
br
What i need is the IP table.tbody.tr.td.aelements text and not the country table.tbody.tr.td.img.aelements.
我需要的是 IPtable.tbody.tr.td.a元素文本而不是国家table.tbody.tr.td.img.a元素。
Are there any experienced users of BeautifulSoup who would have any inkling on how to to this selection and extraction.
是否有任何有经验的 BeautifulSoup 用户对如何进行此选择和提取有任何了解。
Thanks.
谢谢。
回答by m.wasowski
Search just first <td>for each row in tbody:
首先搜索<td>中的每一行tbody：
# html should contain page content:
[row.find('td').getText() for row in bs4.BeautifulSoup(html).find('tbody').find_all('tr')]
or maybe more readable:
或者可能更具可读性：
rows = [row in bs4.BeautifulSoup(html).find('tbody').find_all('tr')]
iplist = [row.find('td').getText() for row in rows]
回答by behzad.nouri
This gives you the right list:
这为您提供了正确的列表：
>>> pred = lambda tag: tag.parent.find('img') is None
>>> list(filter(pred, soup.find('tbody').find_all('a')))
[<a href="hello.html">127.0.0.1<a></a></a>, <a></a>, <a href="hello.html">192.168.0.1<a></a></a>, <a></a>, <a href="hello.html">255.255.255.0<a></a></a>, <a></a>]
just apply .texton the elements of this list.
只需应用于.text此列表的元素。
There are multiple empty <a></a>tags in above list because the <a>tags in the html are not closed properly. To get rid of them, you may use
<a></a>上面列表中有多个空标签，因为<a>html 中的标签没有正确关闭。要摆脱它们，您可以使用
pred = lambda tag: tag.parent.find('img') is None and tag.text
and ultimately:
并最终：
>>> [tag.text for tag in filter(pred, soup.find('tbody').find_all('a'))]
['127.0.0.1', '192.168.0.1', '255.255.255.0']
回答by salmanwahed
You can use a little regular expression for extracting the ip address. BeautifulSoup with regular expression is a nice combination for scraping.
您可以使用一些正则表达式来提取 ip 地址。带有正则表达式的 BeautifulSoup 是一个很好的抓取组合。
ip_pat = re.compile(r"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$")
for row in table.findAll("a"):
if ip_pat.match(row.text):
print(row.text)
回答by unutbu
First note that the HTML is not well-formed. It is not closing the atags. There are two<a>tags started here:
首先请注意，HTML 格式不正确。它不是关闭a标签。这里有两个<a>标签：
<a href="hello.html">127.0.0.1<a>
If you print tableyou'll see BeautifulSoup is parsing the HTML as:
如果您打印，table您会看到 BeautifulSoup 将 HTML 解析为：
<td>
<a href="hello.html">127.0.0.1</a><a></a>
</td>
...
Each ais followed by an empty a.
每个a后跟一个空的a。
Given the presence of those extra <a>tags, if you want every third<a>tag, then
鉴于这些额外<a>标签的存在，如果你想要每三个<a>标签，那么
for row in table.findAll("a")[::3]:
print(row.get_text())
suffices:
足够了：
127.0.0.1
192.168.0.1
255.255.255.0
On the other hand, if the occurrence of <a>tags is not so regular and you only want that <a>tags with no previous sibling (such as, but not limited to <img>), then
另一方面，如果<a>标签的出现不是那么有规律，而您只想要<a>没有以前同级的标签（例如但不限于<img>），那么
for row in table.findAll("a"):
sibling = row.findPreviousSibling()
if sibling is None:
print(row.get_text())
would work.
会工作。
If you have lxml, the criteria can be expressed more succinctly using XPath:
如果您有lxml，则可以使用 XPath 更简洁地表达条件：
import lxml.html as LH
doc = LH.parse("data.htm")
ips = doc.xpath('//table[@class="mainTable"]//td/a[not(preceding-sibling::img)]/text()')
print(ips)
The XPath used above has the following meaning:
上面使用的XPath含义如下：
//table select all <table> tags
[@class="mainTable"] that have a class="mainTable" attribute
// from these tags select descendants
td/a which are td tags with a child <a> tag
[not(preceding-sibling::img)] such that it does not have a preceding sibling <img> tag
/text() return the text of the <a> tag
It does take a little time to learn XPath, but once you learn it you may never want to use BeautifulSoup again.
学习 XPath确实需要一点时间，但是一旦你学会了它，你可能再也不想使用 BeautifulSoup 了。
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