Beautiful soup使用
2018-10-25 本文已影响64人
_Haimei
| 解析器 | 使用方法 | 优势 | 劣势 |
|---|---|---|---|
| Python标准库 | BeautifulSoup(markup, "html.parser") | Python的内置标准库、执行速度适中、文档容错能力强 | Python 2.7.3及Python 3.2.2之前的版本文档容错能力差 |
| lxml HTML解析器 | BeautifulSoup(markup, "lxml") | 速度快、文档容错能力强 | 需要安装C语言库 |
| lxml XML解析器 | BeautifulSoup(markup, "xml") | 速度快、唯一支持XML的解析器 | 需要安装C语言库 |
| html5lib | BeautifulSoup(markup, "html5lib") | 最好的容错性、以浏览器的方式解析文档、生成HTML5格式的文档 | 速度慢、不依赖外部扩展 |
提取标签中的字符串
from bs4 import BeautifulSoup
soup = BeautifulSoup('<p>Hello</p>','lxml')
print(soup.p.string)
Hello
基本用法
html = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
soup.prettify()
'<html>\n <head>\n <title>\n The Dormouse\'s story\n </title>\n </head>\n <body>\n <p class="title" name="dromouse">\n <b>\n The Dormouse\'s story\n </b>\n </p>\n <p class="story">\n Once upon a time there were three little sisters; and their names were\n <a class="sister" href="http://example.com/elsie" id="link1">\n <!-- Elsie -->\n </a>\n ,\n <a class="sister" href="http://example.com/lacie" id="link2">\n Lacie\n </a>\n and\n <a class="sister" href="http://example.com/tillie" id="link3">\n Tillie\n </a>\n ;\nand they lived at the bottom of a well.\n </p>\n <p class="story">\n ...\n </p>\n </body>\n</html>'
soup.title.string
"The Dormouse's story"
节点选择器
选择元素
soup.title
<title>The Dormouse's story</title>
type(soup.title)
bs4.element.Tag
soup.title.string
"The Dormouse's story"
soup.head
<head><title>The Dormouse's story</title></head>
soup.p
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
提取信息
soup.title.name
'title'
获取属性
soup.p.attrs
{'class': ['title'], 'name': 'dromouse'}
soup.p.attrs['name']
'dromouse'
soup.p['name']
'dromouse'
soup.p['class']
['title']
获取内容
soup.p.string
"The Dormouse's story"
嵌套选择
html = """
<html><head><title>The Dormouse's story</title></head>
<body>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
soup.head.title
<title>The Dormouse's story</title>
type(soup.head.title)
bs4.element.Tag
soup.head.title.string
"The Dormouse's story"
关联选择
子节点和子孙节点
html = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
<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">
<span>Elsie</span>
</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>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
soup.p.children
<list_iterator at 0x107d82518>
for i ,child in enumerate(soup.p.children):
print(i,child)
0
Once upon a time there were three little sisters; and their names were
1 <a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
2
3 <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
4
and
5 <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
6
and they lived at the bottom of a well.
soup.p.contents
['\n Once upon a time there were three little sisters; and their names were\n ',
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>,
'\n',
<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>,
' \n and\n ',
<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>,
'\n and they lived at the bottom of a well.\n ']
for i ,child in enumerate(soup.p.descendants):
print(i,child)
0
Once upon a time there were three little sisters; and their names were
1 <a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
2
3 <span>Elsie</span>
4 Elsie
5
6
7 <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
8 Lacie
9
and
10 <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
11 Tillie
12
and they lived at the bottom of a well.
soup.p.descendants
<generator object descendants at 0x107d06518>
父节点和祖先节点
html = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
<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">
<span>Elsie</span>
</a>
</p>
<p class="story">...</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
soup.a.parent
<p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
html = """
<html>
<body>
<p class="story">
<a href="http://example.com/elsie" class="sister" id="link1">
<span>Elsie</span>
</a>
</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
type(soup.a.parents)
generator
list(enumerate(soup.a.parents))
[(0, <p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>), (1, <body>
<p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
</body>), (2, <html>
<body>
<p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
</body></html>), (3, <html>
<body>
<p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
</body></html>)]
兄弟节点
html = """
<html>
<body>
<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">
<span>Elsie</span>
</a>
Hello
<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>
"""
soup = BeautifulSoup(html,'lxml')
soup.a.next_sibling
'\n Hello\n '
soup.a.previous_sibling
'\n Once upon a time there were three little sisters; and their names were\n '
list(enumerate(soup.a.next_siblings))
[(0, '\n Hello\n '),
(1, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>),
(2, ' \n and\n '),
(3, <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>),
(4, '\n and they lived at the bottom of a well.\n ')]
list(enumerate(soup.a.previous_siblings))
[(0,
'\n Once upon a time there were three little sisters; and their names were\n ')]
next_sibling和previous_sibling分别获取节点的下一个和上一个兄弟元素，next_siblings和previous_siblings则分别返回所有前面和后面的兄弟节点的生成器
提取信息
html = """
<html>
<body>
<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">Bob</a><a href="http://example.com/lacie" class="sister" id="link2">Lacie</a>
</p>
"""
soup = BeautifulSoup(html,'lxml')
type(soup.a.next_sibling)
bs4.element.Tag
soup.a.next_sibling
<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
soup.a.next_sibling.string
'Lacie'
type(soup.a.parents)
generator
list(soup.a.parents)[0]
<p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">Bob</a><a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
</p>
list(soup.a.parents)[0].attrs['class']
['story']
如果返回结果是单个节点，那么可以直接调用string、attrs等属性获得其文本和属性；如果返回结果是多个节点的生成器，则可以转为列表后取出某个元素，然后再调用string、attrs等属性获取其对应节点的文本和属性。
方法选择器
find_all(name , attrs , recursive , text , **kwargs)
name
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(name='ul'))
print(type(soup.find_all(name='ul')[0]))
[<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>, <ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>]
<class 'bs4.element.Tag'>
for ul in soup.find_all(name='ul'):
print(ul.find_all(name='li'))
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
for ul in soup.find_all(name='ul'):
print(ul.find_all(name='li'))
for li in ul.find_all(name='li'):
print(li.string)
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
Foo
Bar
Jay
[<li class="element">Foo</li>, <li class="element">Bar</li>]
Foo
Bar
attrs
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(attrs={'id': 'list-1'}))
print(soup.find_all(attrs={'name': 'elements'}))
[<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
[<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(id='list-1'))
print(soup.find_all(class_='element'))
[<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>, <li class="element">Foo</li>, <li class="element">Bar</li>]
text
import re
html='''
<div class="panel">
<div class="panel-body">
<a>Hello, this is a link</a>
<a>Hello, this is a link, too</a>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(text=re.compile('link')))
['Hello, this is a link', 'Hello, this is a link, too']
find()
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find(name='ul'))
print(type(soup.find(name='ul')))
print(soup.find(class_='list'))
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<class 'bs4.element.Tag'>
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
1.find_parents()和find_parent()：前者返回所有祖先节点，后者返回直接父节点。
2.find_next_siblings()和find_next_sibling()：前者返回后面所有的兄弟节点，后者返回后面第一个兄弟节点。
3.find_previous_siblings()和find_previous_sibling()：前者返回前面所有的兄弟节点，后者返回前面第一个兄弟节点。
4.find_all_next()和find_next()：前者返回节点后所有符合条件的节点，后者返回第一个符合条件的节点。
5.find_all_previous()和find_previous()：前者返回节点后所有符合条件的节点，后者返回第一个符合条件的节点。
CSS选择器
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.select('.panel .panel-heading'))
print(soup.select('ul li'))
print(soup.select('#list-2 .element'))
print(type(soup.select('ul')[0]))
[<div class="panel-heading">
<h4>Hello</h4>
</div>]
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>, <li class="element">Foo</li>, <li class="element">Bar</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
<class 'bs4.element.Tag'>
嵌套选择
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.select('ul'):
print(ul.select('li'))
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
获取属性
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.select('ul'):
print(ul['id'])
print(ul.attrs['id'])
list-1
list-1
list-2
list-2
获取文本
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for li in soup.select('li'):
print('Get Text:', li.get_text())
print('String:', li.string)
Get Text: Foo
String: Foo
Get Text: Bar
String: Bar
Get Text: Jay
String: Jay
Get Text: Foo
String: Foo
Get Text: Bar
String: Bar
