python beautiful soup库入门安装教程
pip install beautifulsoup4beautiful soup库的理解
beautiful soup库是解析、遍历、维护“标签树”的功能库
beautiful soup库的引用from bs4 import BeautifulSoupimport bs4BeautifulSoup类
BeautifulSoup对应一个HTML/XML文档的全部内容
回顾demo.htmlimport requestsr = requests.get('http://python123.io/ws/demo.html')demo = r.textprint(demo)
<html><head><title>This is a python demo page</title></head><body><p class='title'><b>The demo python introduces several python courses.</b></p><p class='course'>Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:<a href='http://www.icourse163.org/course/BIT-268001' id='link1'>Basic Python</a> and <a href='http://www.icourse163.org/course/BIT-1001870001' id='link2'>Advanced Python</a>.</p></body></html>Tag标签
基本元素 说明 Tag 标签,最基本的信息组织单元,分别用<>和</>标明开头和结尾
import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')print(soup.title)tag = soup.aprint(tag)
<title>This is a python demo page</title><a href='http://www.icourse163.org/course/BIT-268001' >Basic Python</a>
任何存在于HTML语法中的标签都可以用soup.访问获得。当HTML文档中存在多个相同对应内容时,soup.返回第一个
Tag的name基本元素 说明 Name 标签的名字,
…
的名字是’p’,格式:.nameimport requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')print(soup.a.name)print(soup.a.parent.name)print(soup.a.parent.parent.name)
ap bodyTag的attrs(属性)
基本元素 说明 Attributes 标签的属性,字典形式组织,格式:.attrs
import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')tag = soup.aprint(tag.attrs)print(tag.attrs[’class’])print(tag.attrs[’href’])print(type(tag.attrs))print(type(tag))
{’href’: ’http://www.icourse163.org/course/BIT-268001’, ’class’: [’py1’], ’id’: ’link1’}[’py1’]http://www.icourse163.org/course/BIT-268001<class ’dict’><class ’bs4.element.Tag’>Tag的NavigableString
Tag的NavigableString
基本元素 说明 NavigableString 标签内非属性字符串,<>…</>中字符串,格式:.string
Tag的Comment
基本元素 说明 Comment 标签内字符串的注释部分,一种特殊的Comment类型
import requestsfrom bs4 import BeautifulSoupnewsoup = BeautifulSoup('<b><!--This is a comment--></b><p>This is not a comment</p>','html.parser')print(newsoup.b.string)print(type(newsoup.b.string))print(newsoup.p.string)print(type(newsoup.p.string))
This is a comment<class ’bs4.element.Comment’>This is not a comment<class ’bs4.element.NavigableString’>HTML基本格式标签树的下行遍历
属性 说明 .contents 子节点的列表,将所有儿子结点存入列表 .children 子节点的迭代类型,与.contents类似,用于循环遍历儿子结点 .descendents 子孙节点的迭代类型,包含所有子孙节点,用于循环遍历
BeautifulSoup类型是标签树的根节点
import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')print(soup.head)print(soup.head.contents)print(soup.body.contents)print(len(soup.body.contents))print(soup.body.contents[1])
<head><title>This is a python demo page</title></head>[<title>This is a python demo page</title>][’n’, <p ><b>The demo python introduces several python courses.</b></p>, ’n’, <p >Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:<a href='http://www.icourse163.org/course/BIT-268001' >Basic Python</a> and <a href='http://www.icourse163.org/course/BIT-1001870001' >Advanced Python</a>.</p>, ’n’]5<p ><b>The demo python introduces several python courses.</b></p>
for child in soup.body.children:print(child) #遍历儿子结点for child in soup.body.descendants:print(child) #遍历子孙节点标签树的上行遍历
属性 说明 .parent 节点的父亲标签 .parents 节点先辈标签的迭代类型,用于循环遍历先辈节点
import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')print(soup.title.parent)print(soup.html.parent)
<head><title>This is a python demo page</title></head><html><head><title>This is a python demo page</title></head><body><p ><b>The demo python introduces several python courses.</b></p><p >Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:<a href='http://www.icourse163.org/course/BIT-268001' >Basic Python</a> and <a href='http://www.icourse163.org/course/BIT-1001870001' >Advanced Python</a>.</p></body></html>
import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')for parent in soup.a.parents: if parent is None:print(parent) else:print(parent.name)
pbody html [document]标签的平行遍历属性 说明 .next_sibling 返回按照HTML文本顺序的下一个平行节点标签 .previous.sibling 返回按照HTML文本顺序的上一个平行节点标签 .next_siblings 迭代类型,返回按照HTML文本顺序的后续所有平行节点标签 .previous.siblings 迭代类型,返回按照HTML文本顺序的前续所有平行节点标签
import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')print(soup.a.next_sibling)print(soup.a.next_sibling.next_sibling)print(soup.a.previous_sibling)print(soup.a.previous_sibling.previous_sibling)print(soup.a.parent)
and <a href='http://www.icourse163.org/course/BIT-1001870001' id='link2'>Advanced Python</a>Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:None<p class='course'>Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:<a href='http://www.icourse163.org/course/BIT-268001' id='link1'>Basic Python</a> and <a href='http://www.icourse163.org/course/BIT-1001870001' id='link2'>Advanced Python</a>.</p>
for sibling in soup.a.next_sibling:print(sibling) #遍历后续节点for sibling in soup.a.previous_sibling:print(sibling) #遍历前续节点
bs库的prettify()方法import requestsfrom bs4 import BeautifulSoupr = requests.get('http://python123.io/ws/demo.html')demo = r.textsoup = BeautifulSoup(demo,'html.parser')print(soup.prettify())
<html> <head> <title> This is a python demo page </title> </head> <body> <p class='title'> <b> The demo python introduces several python courses. </b> </p> <p class='course'> Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses: Basic Python </a> and <a href='http://www.icourse163.org/course/BIT-1001870001' id='link2'> Advanced Python </a> . </p> </body></html>
.prettify()为HTML文本<>及其内容增加更加’n’.prettify()可用于标签,方法:.prettify()
bs4库的编码bs4库将任何HTML输入都变成utf-8编码python 3.x默认支持编码是utf-8,解析无障碍
import requestsfrom bs4 import BeautifulSoupsoup = BeautifulSoup('<p>中文</p>','html.parser')print(soup.p.string)print(soup.p.prettify())
中文<p> 中文</p>
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