python beautiful soup庫入門安裝教程
發(fā)布日期：2022-02-02 15:22 | 文章來源：站長之家
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(hù)“標(biāo)簽樹”的功能庫
beautiful soup庫的引用
from bs4 import BeautifulSoup import bs4
BeautifulSoup類
BeautifulSoup對應(yīng)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(biāo)簽
| 基本元素 | 說明 |
|---|---|
| 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語法中的標(biāo)簽都可以用soup.訪問獲得。當(dāng)HTML文檔中存在多個相同對應(yīng)內(nèi)容時，soup.返回第一個
Tag的name
| 基本元素 | 說明 |
|---|---|
| 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
Tag的NavigableString
| 基本元素 | 說明 |
|---|---|
| NavigableString | 標(biāo)簽內(nèi)非屬性字符串，<>…</>中字符串，格式：.string |
| 基本元素 | 說明 |
|---|---|
| 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(biāo)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(biāo)簽樹的上行遍歷
| 屬性 | 說明 |
|---|---|
| .parent | 節(jié)點的父親標(biāo)簽 |
| .parents | 節(jié)點先輩標(biāo)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(biāo)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(biāo)簽 |
| .previous.sibling | 返回按照HTML文本順序的上一個平行節(jié)點標(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 for sibling in soup.a.previous_sibling: print(sibling) #遍歷前續(xù)節(jié)點
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(biāo)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(rèn)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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