PYTHON 爬虫笔记五:BeautifulSoup库基础用法
知识点一:BeautifulSoup库详解及其基本使用方法
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什么是BeautifulSoup
灵活又方便的网页解析库,处理高效,支持多种解析器。利用它不用编写正则表达式即可方便实现网页信息的提取库。
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BeautifulSoup中常见的解析库
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基本用法:
html = ''' <html><head><title>The Domouse'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 little sisters;and their names were <a href="http://example.com/elsie"class="sister"id="link1"><!--Elsie--></a> <a hred="http://example.com/lacle"class="sister"id="link2">Lacle</a>and <a hred="http://example.com/tilie"class="sister"id="link3">Tillie</a> and they lived at bottom of a well.</p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup= BeautifulSoup(html,'lxml') print(soup.prettify())#格式化代码,打印结果自动补全缺失的代码 print(soup.title.string)#文章标题
<html> <head> <title> The Domouse'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 little sisters;and their names were <a class="sister" href="http://example.com/elsie" id="link1"> <!--Elsie--> </a> <a class="sister" hred="http://example.com/lacle" id="link2"> Lacle </a> and <a class="sister" hred="http://example.com/tilie" id="link3"> Tillie </a> and they lived at bottom of a well. </p> <p class="story"> ... </p> </body> </html> The Domouse's story
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标签选择器
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选择元素
html = ''' <html><head><title>The Domouse'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 little sisters;and their names were <a href="http://example.com/elsie"class="sister"id="link1"><!--Elsie--></a> <a hred="http://example.com/lacle"class="sister"id="link2">Lacle</a>and <a hred="http://example.com/tilie"class="sister"id="link3">Tillie</a> and they lived at bottom of a well.</p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml')
print(soup.title) #<title>The Domouse's story</title> print(type(soup.title)) #<class 'bs4.element.Tag'> print(soup.head) #<head><title>The Domouse's story</title></head> print(soup.p)#当出现多个时,只返回第一个 #<p class="title" name="dromouse"><b>The Dormouse's story</b></p> -
获取标签名称
html = ''' <html><head><title>The Domouse'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 little sisters;and their names were <a href="http://example.com/elsie"class="sister"id="link1"><!--Elsie--></a> <a hred="http://example.com/lacle"class="sister"id="link2">Lacle</a>and <a hred="http://example.com/tilie"class="sister"id="link3">Tillie</a> and they lived at bottom of a well.</p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml')
print(soup.title.name) #title -
获取属性
html = ''' <html><head><title>The Domouse'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 little sisters;and their names were <a href="http://example.com/elsie"class="sister"id="link1"><!--Elsie--></a> <a hred="http://example.com/lacle"class="sister"id="link2">Lacle</a>and <a hred="http://example.com/tilie"class="sister"id="link3">Tillie</a> and they lived at bottom of a well.</p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') print(soup.p.attrs['name']) #dromouse print(soup.p['name']) #dromouse
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获取标签内容
html = ''' <html><head><title>The Domouse'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 little sisters;and their names were <a href="http://example.com/elsie"class="sister"id="link1"><!--Elsie--></a> <a hred="http://example.com/lacle"class="sister"id="link2">Lacle</a>and <a hred="http://example.com/tilie"class="sister"id="link3">Tillie</a> and they lived at bottom of a well.</p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') print(soup.p.string) #The Dormouse's story
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嵌套选择
html = ''' <html><head><title>The Domouse'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 little sisters;and their names were <a href="http://example.com/elsie"class="sister"id="link1"><!--Elsie--></a> <a hred="http://example.com/lacle"class="sister"id="link2">Lacle</a>and <a hred="http://example.com/tilie"class="sister"id="link3">Tillie</a> and they lived at bottom of a well.</p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') print(type(soup.title)) #<class 'bs4.element.Tag'> print(soup.head.title.string)#观察html的代码,其中有一层包含的关系:head(title),那我们就可以用嵌套的形式将其内容打印出来;body(p或是a) #The Domouse's story
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子节点和子孙节点
#获取标签的子节点 html2 = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup2 = BeautifulSoup(html2,'lxml') print(soup2.p.contents)
['\n Once upon a time there were little sisters;and their names were\n ', <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a>, '\n', <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a>, '\n and\n ', <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a>, '\n and they lived at bottom of a well.\n ']
另一中方法:
#获取标签的子节点 html2 = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html2,'lxml') print(soup.children)#不同之处:children实际上是一个迭代器,需要用循环的方式才能将内容取出 for i,child in enumerate(soup.p.children): print(i,child)
<list_iterator object at 0x00000208F026B400> 0 Once upon a time there were little sisters;and their names were 1 <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> 2 3 <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> 4 and 5 <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> 6 and they lived at bottom of a well.
不同之处:children实际上是一个迭代器,需要用循环的方式才能将内容取出,而子节点只是一个列表
#获取标签的子孙节点 html2 = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html2,'lxml') print(soup2.p.descendants)#获取所有的子孙节点,也是一个迭代器 for i,child in enumerate(soup2.p.descendants): print(i,child)
<generator object descendants at 0x00000208F0240AF0> 0 Once upon a time there were little sisters;and their names were 1 <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> 2 3 <span>Elsle</span> 4 Elsle 5 6 7 <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> 8 Lacle 9 and 10 <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> 11 Tillie 12 and they lived at bottom of a well.
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父节点和祖先节点
#父节点 html = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') print(soup.a.parent)
<p class="story"> Once upon a time there were little sisters;and their names were <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> and <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> and they lived at bottom of a well. </p>
#获取祖先节点 html = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') print(list(enumerate(soup.a.parents)))#所有祖先节点(爸爸也算)
[(0, <p class="story"> Once upon a time there were little sisters;and their names were <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> and <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> and they lived at bottom of a well. </p>), (1, <body> <p class="story"> Once upon a time there were little sisters;and their names were <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> and <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> </body>), (2, <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> and <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> </body></html>), (3, <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a class="sister" href="http://example.com/elsie" id="link1"> <span>Elsle</span> </a> <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a> and <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> </body></html>)]
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兄弟节点
#获取前兄弟节点 html = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') #兄弟节点(与之并列的节点) print(list(enumerate(soup.a.previous_siblings)))#前面的兄弟节点
[(0, '\n Once upon a time there were little sisters;and their names were\n ')]
html = ''' <html> <head> <title>The Domouse's story</title> </head> <body> <p class="story"> Once upon a time there were little sisters;and their names were <a href="http://example.com/elsie" class="sister"id="link1"> <span>Elsle</span> </a> <a hred="http://example.com/lacle"class="sister" id="link2">Lacle</a> and <a hred="http://example.com/tilie"class="sister" id="link3">Tillie</a> and they lived at bottom of a well. </p> <p class="story">...</p> ''' from bs4 import BeautifulSoup soup = BeautifulSoup(html,'lxml') #兄弟节点(与之并列的节点) print(list(enumerate(soup.a.next_siblings)))#后面的兄弟节点
[(0, '\n'), (1, <a class="sister" hred="http://example.com/lacle" id="link2">Lacle</a>), (2, '\n and\n '), (3, <a class="sister" hred="http://example.com/tilie" id="link3">Tillie</a>), (4, '\n and they lived at bottom of a well.\n ')]
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标准选择器
find_all(name,attrs,recursive,text,**kwargs)
可以根据标签名,属性,内容查找文档
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根据name查找
html = ''' <div class="panel"> <div class="panel-heading"name="elements"> <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('ul'))#列表类型 print(type(soup.find_all('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'>
html = ''' <div class="panel"> <div class="panel-heading"name="elements"> <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') for ul in soup.find_all('ul'): print(ul.find_all('li'))#层层嵌套的查找
[<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>]
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根据attrs查找
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>]
另一种方式
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(id='list-1')) print(soup.find_all(class_='element'))
[<ul class="list" id="list-1"> <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>]
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根据text查找
#text html = ''' <div class="panel"> <div class="panel-heading"> <h4>Hello</h4> </div> <div class="panel-body"name="elelments"> <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(text='Foo')) #['Foo', 'Foo']
find(name,attrs,recursive,text,**kwargs)返回单个元素,find_all返回所有元素
html = ''' <div class="panel"> <div class="panel-heading"> <h4>Hello</h4> </div> <div class="panel-body"name="elelments"> <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('ul')) print(type(soup.find('ul'))) print(soup.find('page'))
<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'> None
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其他方法
如果使用find方法,返回单个元素 find_parents()返回所有祖先节点 find_parent()返回直接父节点 find_next_siblings()返回后面所有兄弟节点 find_next_sibling()返回后面第一个兄弟节点 find_previous_siblings()返回前面所有的兄弟节点 find_previous_sibling()返回前面第一个的兄弟节点 find_all_next()返回节点后所有符合条件的节点 find_next()返回节点后第一个符合条件的节点 find_all_previous()返回节点后所有符合条件的节点 find_previous()返回第一个符合条件的节点
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CSS选择器(通过select()直接传入CSS选择器即可完成选择)
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html = ''' <div class="panel"> <div class="panel-heading"> <h4>Hello</h4> </div> <div class="panel-body"name="elelments"> <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')) #class就需要加一个“.” print(soup.select('ul li')) #选择标签 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'>
另一种方法:
html = ''' <div class="panel"> <div class="panel-heading"> <h4>Hello</h4> </div> <div class="panel-body"name="elelments"> <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') for ul in soup.select('ul'):#直接print(soup.select('ul li')) 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>]
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获取属性
html = ''' <div class="panel"> <div class="panel-heading"> <h4>Hello</h4> </div> <div class="panel-body"name="elelments"> <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') for ul in soup.select('ul'): print(ul['id'])#直接用[] print(ul.attrs['id'])#或是attrs+[]
list-1 list-1 list-2 list-2
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获取内容
html = ''' <div class="panel"> <div class="panel-heading"> <h4>Hello</h4> </div> <div class="panel-body"name="elelments"> <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') for li in soup.select('li'): print(li['class'], li.get_text())
['element'] Foo ['element'] Bar ['element'] Jay ['element'] Foo ['element'] Bar
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总结
推荐使用'lxml'解析库,必要时使用html.parser
标签选择器筛选功能但速度快
建议使用find(),find_all()查询匹配单个结果或者多个结果
如果对CSS选择器熟悉建议选用select()
记住常用的获取属性和文本值得方法
这都是我对自己学习过程的理解,如有错误请指出!我算一个小白了。