python beautiful soup庫入門安裝教程
pip install beautifulsoup4beautiful soup庫的理解
beautiful soup庫是解析、遍歷、維護“標簽樹”的功能庫
beautiful soup庫的引用from bs4 import BeautifulSoupimport bs4BeautifulSoup類
BeautifulSoup對應一個HTML/XML文檔的全部內容
回顧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 id='link1'>Basic Python</a> and <a id='link2'>Advanced Python</a>.</p></body></html>Tag標簽
基本元素 說明 Tag 標簽，最基本的信息組織單元，分別用<>和</>標明開頭和結尾
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 >Basic Python</a>
任何存在于HTML語法中的標簽都可以用soup.訪問獲得。當HTML文檔中存在多個相同對應內容時，soup.返回第一個
Tag的name基本元素 說明 Name 標簽的名字，
…
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（屬性）
基本元素 說明 Attributes 標簽的屬性，字典形式組織，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 說明 NavigableString 標簽內非屬性字符串，<>…</>中字符串，格式：.string
Tag的Comment
基本元素 說明 Comment 標簽內字符串的注釋部分，一種特殊的Comment類型
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基本格式標簽樹的下行遍歷
屬性 說明 .contents 子節點的列表，將所有兒子結點存入列表 .children 子節點的迭代類型，與.contents類似，用于循環遍歷兒子結點 .descendents 子孫節點的迭代類型，包含所有子孫節點，用于循環遍歷
BeautifulSoup類型是標簽樹的根節點
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 >Basic Python</a> and <a >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) #遍歷兒子結點for child in soup.body.descendants:print(child) #遍歷子孫節點標簽樹的上行遍歷
屬性 說明 .parent 節點的父親標簽 .parents 節點先輩標簽的迭代類型，用于循環遍歷先輩節點
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 >Basic Python</a> and <a >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]標簽的平行遍歷屬性 說明 .next_sibling 返回按照HTML文本順序的下一個平行節點標簽 .previous.sibling 返回按照HTML文本順序的上一個平行節點標簽 .next_siblings 迭代類型，返回按照HTML文本順序的后續所有平行節點標簽 .previous.siblings 迭代類型，返回按照HTML文本順序的前續所有平行節點標簽
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 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 id='link1'>Basic Python</a> and <a id='link2'>Advanced Python</a>.</p>
for sibling in soup.a.next_sibling:print(sibling) #遍歷后續節點for sibling in soup.a.previous_sibling:print(sibling) #遍歷前續節點
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 id='link2'> Advanced Python </a> . </p> </body></html>
.prettify()為HTML文本<>及其內容增加更加’n’.prettify()可用于標簽，方法：.prettify()
bs4庫的編碼bs4庫將任何HTML輸入都變成utf-8編碼python 3.x默認支持編碼是utf-8,解析無障礙
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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