网络爬虫_第二章_提取_第四单元_BeautifulSoup库入门(未完待续)

1.Beautiful Soup库的基本元素

Beautiful Soup库的理解

　　　　　　　　　 　　<p>..</p>: 标签：Tag<p> p指的是标签的名字， Name成对出现<p class="title">...</p>属性Attributes0个或多个（由键值对构成）

Beautiful Soup库的引用

            引用方式from bs4 import BeautifulSoup使用方法from bs4 import BeautifulSoup1. soup = BeautifulSoup("<html>data<html>", "html.parser")2. soup = BeautifulSoup(open("D://demo.html"), "html.parser")BeautifulSoup对应一个HTML/XML文档的全部内容。

Beautiful Soup库解析器

soup = BeautifulSoup('<html>data</html>'，'html.parser')

分类　　

          解析器                     使用方法                                  条件bs4的HTML解析器         BeautifulSoup(mk,'html.parser')               安装bs4库lxml的HTML解析器      BeautifulSoup(mk,'lxml')                  pip install lxmllxml的XML解析器         BeautifulSoup(mk,'xml')                   pip install lxmlhtml5lib的解析器        BeautifulSoup(mk,'html5lib')　              pip install html5lib

Beautiful Soup类基本元素

<p class=“title”> … </p>

分类　　

    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Name            标签的名字，<p>…</p>的名字是'p'，格式：<tag>.nameAttributes      标签的属性，字典形式组织，格式：<tag>.attrsNavigableString 标签内非属性字符串，<>…</>中字符串，格式：<tag>.stringComment        标签内字符串的注释部分，一种特殊的Comment类型

具体使用代码

1. 回顾demo.html

 import requestsurl2 = "http://python123.io/ws/demo.html"r = requests.get(url2)demo = r.textprint(demo)打印输出# 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 href="http://www.icourse163.org/course/BIT-268001" class="py1" id="link1">Basic Python</a> and <a href="http://www.icourse163.org/course/BIT-1001870001" class="py2" id="link2">Advanced Python</a>.</p></body></html>

2. Tag 标签

Tag 标签，最基本的信息组织单元，分别用<>和</>标明开头和结尾
任何存在于HTML语法中的标签都可以用soup.<tag>访问获得
当HTML文档中存在多个相同<tag>对应内容时，soup.<tag>返回第一个

from bs4 import BeautifulSoup
import requestsurl = "http://python123.io/ws/demo.html"
r = requests.get(url)
demo = r.text
soup = BeautifulSoup(demo, "html.parser")
print(soup.title)
tag = soup.a
print(tag)打印输出# print(soup.title)<title>This is a python demo page</title># print(tag)<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a>

3. Tag的name（名字）

Name 标签的名字，<p>…</p>的名字是'p'，格式：<tag>.name
每个<tag>都有自己的名字，通过<tag>.name获取，字符串类型

from bs4 import BeautifulSoupimport requestsurl2 = "http://python123.io/ws/demo.html"r = requests.get(url2)demo = r.textsoup = BeautifulSoup(demo, "html.parser")print(soup.a.name)print(soup.a.parent.name)print(soup.a.parent.parent.name)打印输出#   print(soup.a.name)'a'# print(soup.a.parent.name)'p'# print(soup.a.parent.parent.name)'body'

4. Tag的attrs（属性）

Attributes 标签的属性，字典形式组织，格式：<tag>.attrs
一个<tag>可以有0或多个属性，字典类型

from bs4 import BeautifulSoup
import requests
url2 = "http://python123.io/ws/demo.html"
r = requests.get(url2)
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))
打印输出# print(tag.attrs){'href': 'http://www.icourse163.org/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}# print(tag.attrs['class'])['py1']#   print(tag.attrs['href'])http://www.icourse163.org/course/BIT-268001# print(type(tag.attrs))<class 'dict'># print(type(tag))<class 'bs4.element.Tag'>

5. Tag的NavigableString　

NavigableString 标签内非属性字符串，<>…</>中字符串，格式：<tag>.string
NavigableString可以跨越多个层次

from bs4 import BeautifulSoup
import requests
url2 = "http://python123.io/ws/demo.html"
r = requests.get(url2)
demo = r.text
soup = BeautifulSoup(demo, "html.parser")
soup.a
print(soup.a.string)
print(soup.p)
print(soup.p.string)
print(type(soup.p.string))
打印输出#   print(soup.a.string)Basic Python# print(soup.p)<p class="title"><b>The demo python introduces several python courses.</b></p># print(soup.p.string)The demo python introduces several python courses.# print(type(soup.p.string))<class 'bs4.element.NavigableString'>

6. Tag的Comment

Comment 标签内字符串的注释部分，一种特殊的Comment类型
Comment是一种特殊类型

from bs4 import BeautifulSoup
import requests
demo = "<b><!--This is a commet--></b><p>This is not a comment</p>"
newsoup = BeautifulSoup(demo, "html.parser")
print(newsoup.b.string)
print(newsoup.p.string)
print(type(newsoup.p.string))打印输出# print(newsoup.b.string)This is a commet# print(newsoup.p.string)This is not a comment# print(type(newsoup.p.string))<class 'bs4.element.NavigableString'>

2.Beautiful Soup库的基本元素

RRR

转载于:https://www.cnblogs.com/Robin5/p/11229881.html