13 `bs_ duixiang. Tag tag ` get a tag object

13 bs_duixiang.tag label Get one tag object

• 13.1 BeautifulSoup Class to extract data
• 13.2 Node selector
  • 1. What is a node
  • 2. Extract node
• 13.3 summary

13.1 BeautifulSoup Class to extract data

The function of selector ： operation BeautifulSoup object , lookup 、 Positioning elements , And extract the data .

13_BeautifulSoup Extract the data 1

13.2 Node selector

1. What is a node

<h1> First level title </h1> 
<h2> Secondary title </h2>   
<h3> Three level title </h3>   
<p> I'm a paragraph </p>    

The above code is a section HTML Code .
h Represents a title label . The title tag has a total of 6 individual , from h1 To h6, The greater the number , The smaller the font size .
p Indicates a paragraph label , Used to segment a paragraph , Monopolize one line on the web page .

stay HTML In the code, I put hp be called HTML label .
stay Python in , We put hp It's called a node label , namely tag label .
【 reminder 】 This statement is more convenient for beginners to understand nodes , It is different from many official textbooks , For reference only .

2. Extract node

Grammar format ：bs object .tag name
tag Refers to the node name .
Return value ： Node object .

use html.parser The parser extracts h2 node

html_str = """
<h2> Farewell my concubine </h2>
<span> In mainland China 、 Hong Kong, China, </span>
<span>171 minute </span>
<h3> synopsis </h3>
<a href="https://maoyan.com/"></a>
"""
#  step 1： from bs4  Import... In the library BeautifulSoup class 
from bs4 import BeautifulSoup

#  step 2： Pass in the parameter , Instantiation BeautifulSoup class 
#  Parameters 1 Is to be parsed HTML character string 
#  Parameters 2 It's a parser （ Here we use html.parser Parser ）
#  After instantiation, you get a BeautifulSoup object 
# bs_duixiang = <class 'bs4.BeautifulSoup'>
bs_duixiang  = BeautifulSoup(html_str, 'html.parser')
print(" After parsing, the parser gets a BeautifulSoup object ：")
print(type(bs_duixiang ),'\n')

# bs object .tag Name extraction node 
print(" Extract here h2 node ")
print(bs_duixiang.h2,'\n')

print(" The extracted node data type is tag object ：")
print(type(bs_duixiang .h2))

【 Terminal output 】

 After parsing, the parser gets a BeautifulSoup object ：
<class 'bs4.BeautifulSoup'> 

 Extract here h2 node 
<h2> Farewell my concubine </h2> 

 The extracted node data type is tag object ：
<class 'bs4.element.Tag'>

After running the code , Successfully output h2 node .

use lxml The parser extracts span node

html_str = """
<h2> Farewell my concubine </h2>
<span> In mainland China 、 Hong Kong, China, </span>
<span>171 minute </span>
<h3> synopsis </h3>
<a href="https://maoyan.com/"></a>
"""
#  step 1： from bs4  Import... In the library BeautifulSoup class 
from bs4 import BeautifulSoup

#  step 2： Pass in the parameter , Instantiation BeautifulSoup class 
#  Parameters 1 Is to be parsed HTML character string 
#  Parameters 2 It's a parser （ Here we use lxml Parser ）
#  After instantiation, you get a BeautifulSoup object 
# bs_duixiang = <class 'bs4.BeautifulSoup'>
bs_duixiang  = BeautifulSoup(html_str, 'lxml')
print(" After parsing, the parser gets a BeautifulSoup object ：")
print(type(bs_duixiang ),'\n')

# bs object .tag Name extraction node 
print(" Extract here span node ")
print(bs_duixiang.span,'\n')

print(" The extracted node data type is tag object ：")
print(type(bs_duixiang .span))

【 Terminal output 】

 After parsing, the parser gets a BeautifulSoup object ：
<class 'bs4.BeautifulSoup'> 

 Extract here span node 
<span> In mainland China 、 Hong Kong, China, </span> 

 The extracted node data type is tag object ：
<class 'bs4.element.Tag'>

Above html_str There is... In the character 2 individual label .
After the code runs successfully , We extracted In mainland China 、 Hong Kong, China, label .
namely 2 individual Number... In the label 1 individual .
That's because of dang html There are multiple identical nodes in the code , The node selector will only extract the 1 Nodes .

13.3 summary

14_ Web crawler 1