Getting reptile -BeautifulSoup4 use

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CSS selectors: BeautifulSoup4

installation:pip install beautifulsoup4
Official documents: http: //beautifulsoup.readthedocs.io/zh_CN/v4.4.0

BeautifulSoup 用来解析 HTML 比较简单，API非常人性化，支持CSS选择器、
Python标准库中的HTML解析器，也支持 lxml 的 XML解析器。

Use the library must first be imported bs4

Parser

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from bs4 import BeautifulSoup

from bs4 import BeautifulSoup

html = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1"><!-- Elsie --></a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p> <p class="story">...</p> 
"""

#创建 Beautiful Soup 对象 
soup = BeautifulSoup(html,'lxml') 
#打开本地 HTML 文件的方式来创建对象 
#soup = BeautifulSoup(open('index.html')) 
#格式化输出 soup 对象的内容 
print(soup.prettify())

Four types of objects

Beautiful Soup complex HTML documents converted into a complex tree structure, each node is Python objects, all objects can be grouped into four kinds:

《1》Tag：Tag 通俗点讲就是 HTML 中的一个个标签

《2》NavigableString：字符串常被包含在tag内.Beautiful Soup用NavigableString类来包装tag中的字符串:通过string来获得。

《3》BeautifulSoup：BeautifulSoup 对象表示的是一个文档的内容。大部分时候,可以把它当作 Tag 对象，
是一个特殊的 Tag，我们可以分别获取它的类型，名称，以及属性

《4》Comment：Comment 对象是一个特殊类型的 NavigableString 对象，其输出的内容不包括注释符号。

Selector

This is another One and find_all way to find a method the same purpose in. When writing CSS, the tag name without any modification, before class names., Before the id plus # we can also use a similar method to screen elements here, with the method is soup.select (), return type is List
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. 1) by the tag name lookup

soup.select('title') 
soup.select('b')

2) Find by class name

print soup.select('.sister')

3) Find the id name

print soup.select('#link1')

4) Find a combination

print soup.select('p #link1')

5) Find a property

print(soup.select('a[class="sister"]'))
soup.select('a[href="http://example.com/elsie"]')

Access to content

soup = BeautifulSoup(html, 'lxml') 
print (type(soup.select('title')))
print (soup.select('title')[0].get_text())
for title in soup.select('title'):
	print (title.get_text()) 
	print (title.attrs['class'])