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python beautiful soup庫(kù)入門安裝教程

beautiful soup庫(kù)的安裝

pip install beautifulsoup4

beautiful soup庫(kù)的理解

beautiful soup庫(kù)是解析、遍歷、維護(hù)“標(biāo)簽樹”的功能庫(kù)

beautiful soup庫(kù)的引用

from bs4 import BeautifulSoup
import bs4

BeautifulSoup類

BeautifulSoup對(duì)應(yīng)一個(gè)HTML/XML文檔的全部?jī)?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(biāo)簽

基本元素	說(shuō)明
Tag	標(biāo)簽，最基本的信息組織單元，分別用>和/>標(biāo)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(yǔ)法中的標(biāo)簽都可以用soup.訪問(wèn)獲得。當(dāng)HTML文檔中存在多個(gè)相同對(duì)應(yīng)內(nèi)容時(shí)，soup.返回第一個(gè)

Tag的name

基本元素	說(shuō)明
Name	標(biāo)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(shuō)明
Attributes	標(biāo)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(shuō)明
NavigableString	標(biāo)簽內(nèi)非屬性字符串，>…/>中字符串，格式：.string

Tag的Comment

基本元素	說(shuō)明
Comment	標(biāo)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(biāo)簽樹的下行遍歷

屬性	說(shuō)明
.contents	子節(jié)點(diǎn)的列表，將所有兒子結(jié)點(diǎn)存入列表
.children	子節(jié)點(diǎn)的迭代類型，與.contents類似，用于循環(huán)遍歷兒子結(jié)點(diǎn)
.descendents	子孫節(jié)點(diǎn)的迭代類型，包含所有子孫節(jié)點(diǎn)，用于循環(huán)遍歷

BeautifulSoup類型是標(biāo)簽樹的根節(jié)點(diǎn)

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

標(biāo)簽樹的上行遍歷

屬性	說(shuō)明
.parent	節(jié)點(diǎn)的父親標(biāo)簽
.parents	節(jié)點(diǎn)先輩標(biāo)簽的迭代類型，用于循環(huán)遍歷先輩節(jié)點(diǎn)

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(biāo)簽的平行遍歷

屬性	說(shuō)明
.next_sibling	返回按照HTML文本順序的下一個(gè)平行節(jié)點(diǎn)標(biāo)簽
.previous.sibling	返回按照HTML文本順序的上一個(gè)平行節(jié)點(diǎn)標(biāo)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(diǎn)標(biāo)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(diǎn)標(biāo)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(diǎn)
for sibling in soup.a.previous_sibling:
	print(sibling)  #遍歷前續(xù)節(jié)點(diǎn)

bs庫(kù)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(biāo)簽，方法：.prettify()

bs4庫(kù)的編碼

bs4庫(kù)將任何HTML輸入都變成utf-8編碼
python 3.x默認(rèn)支持編碼是utf-8,解析無(wú)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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