from bs4 import BeautifulSoup
html = """
<html><head><title>The Dormouse's story</title></head>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
soup = BeautifulSoup(html,'lxml')
我想获取a标签下，href的值，或者获取 id和class 的值，怎么操作呢，请教！
```python
from bs4 import BeautifulSoup
import re
html = """
<html><head><title>The Dormouse's story</title></head>
<p class="title"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
soup = BeautifulSoup(html, 'lxml')
code_url = re.findall('<a class="(.*?)"\shref="(.*?)"\sid="(.*?)">.*?</a>',str(soup), re.S)
print(code_url)
[('sister', 'http://example.com/elsie', 'link1'), ('sister', 'http://example.com/lacie', 'link2'), ('sister', 'http://example.com/tillie', 'link3')]
```
imgs=soup.select('a')
url=imgs[1]['href']
print(url)