python beautiful soup庫入門安裝教程

更新時間：2021年08月30日 14:31:21 作者：Cachel wood

Beautiful Soup是python的一個庫，最主要的功能是從網(wǎng)頁抓取數(shù)據(jù)。今天通過本文給大家分享python beautiful soup庫入門教程，需要的朋友參考下吧

beautiful soup庫的安裝

pip install beautifulsoup4

beautiful 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 BeautifulSoup
import bs4

BeautifulSoup類

BeautifulSoup對應一個HTML/XML文檔的全部內(nèi)容

回顧demo.html

import requests

r = requests.get("http://python123.io/ws/demo.html")
demo = r.text
print(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  class="py1" id="link1">Basic Python</a> and <a  class="py2" 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(jié)尾

import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.title)
tag = soup.a
print(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(nèi)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：.name

import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
print(soup.a.name)
print(soup.a.parent.name)
print(soup.a.parent.parent.name)

a
p   
body

Tag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 requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text
soup = BeautifulSoup(demo,"html.parser")
tag = soup.a
print(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

基本元素	說明
NavigableString	標簽內(nèi)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(nèi)字符串的注釋部分，一種特殊的Comment類型

import requests
from bs4 import BeautifulSoup
newsoup = 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(jié)點的列表，將所有兒子結(jié)點存入列表
.children	子節(jié)點的迭代類型，與.contents類似，用于循環(huán)遍歷兒子結(jié)點
.descendents	子孫節(jié)點的迭代類型，包含所有子孫節(jié)點，用于循環(huán)遍歷

BeautifulSoup類型是標簽樹的根節(jié)點

import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text

soup = 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(jié)點
for child in soup.body.descendants:
	print(child) #遍歷子孫節(jié)點

標簽樹的上行遍歷

屬性	說明
.parent	節(jié)點的父親標簽
.parents	節(jié)點先輩標簽的迭代類型，用于循環(huán)遍歷先輩節(jié)點

import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text

soup = 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 requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text

soup = BeautifulSoup(demo,"html.parser")
for parent in soup.a.parents:
    if parent is None:
        print(parent)
    else:
        print(parent.name)

p
body      
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(jié)點標簽
.previous.sibling	返回按照HTML文本順序的上一個平行節(jié)點標簽
.next_siblings	迭代類型，返回按照HTML文本順序的后續(xù)所有平行節(jié)點標簽
.previous.siblings	迭代類型，返回按照HTML文本順序的前續(xù)所有平行節(jié)點標簽

import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text

soup = 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 class="py2"  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 class="py1"  id="link1">Basic Python</a> and <a class="py2"  id="link2">Advanced Python</a>.</p>

for sibling in soup.a.next_sibling:
	print(sibling)  #遍歷后續(xù)節(jié)點
for sibling in soup.a.previous_sibling:
	print(sibling)  #遍歷前續(xù)節(jié)點

在這里插入圖片描述

bs庫的prettify()方法

import requests
from bs4 import BeautifulSoup
r = requests.get("http://python123.io/ws/demo.html")
demo = r.text

soup = 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 class="py2"  id="link2">
    Advanced Python
   </a>
   .
  </p>
 </body>
</html>

.prettify()為HTML文本<>及其內(nèi)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 requests
from bs4 import BeautifulSoup

soup = 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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