12 initialization of beautifulsoup class

12 BeautifulSoup Class initialization

beautifulsoup4 Shorthand for bs4.
bs4 Kuo is Python Third party library .
The function is to extract data from documents .

bs4 It's the library .
BeautifulSoup It's a class .

【 Knowledge review 】
The first letter of the class should be capitalized .
Class instantiation syntax ： object = Class name ( Parameters )

12.1 BeautifulSoup Class initialization method

1. Initialization steps

2. initialization BeautifulSoup object

#  from bs4 Import... In the library BeautifulSoup  class  
from bs4 import BeautifulSoup

#  Pass in markup、features2 Parameters , Get an instantiated object 
#  object  =  Class name ( Parameters ) 
soup = BeautifulSoup(markup=, features=)

12.2 BeautifulSoup The meaning of the parameter

1. Parameters markup

Parameters markup Refers to the resolved HTML String or file content .

1. Use string variables

#  from bs4 Import... In the library BeautifulSoup  class  
from bs4 import BeautifulSoup

# html_str Is a string variable , It is usually obtained from the previous step HTML Code 
soup = BeautifulSoup(html_str)

2. Use open() Function to open a file

#  from bs4 Import... In the library BeautifulSoup  class  
from bs4 import BeautifulSoup

#  Use open Function to open the file , Get the file object 
#  File objects can also be used as initialization parameters 
# index.html finger HTML Code 
soup = BeautifulSoup(open(index.html))

2. Parameters features

Parameters features Refers to the type of parser

1. Specify the parser

#  from bs4 Import... In the library BeautifulSoup  class  
from bs4 import BeautifulSoup

# html_str  To parse HTML Code ( The data type is string )
#  The parser is 'lxml', Notice the quotation marks around the parser 
#  object  =  Class name ( Parameters ) 
soup = BeautifulSoup(html_str, 'lxml')

#  from bs4 Import... In the library BeautifulSoup  class  
from bs4 import BeautifulSoup

# html_str  To parse HTML Code ( The data type is string )
#  The parser is 'html.parser', Notice the quotation marks around the parser 
#  object  =  Class name ( Parameters ) 
soup = BeautifulSoup(html_str, 'html.parser')

2. Parser not specified , BeautifulSoup Select the default parser to parse the document

#  from bs4 Import... In the library BeautifulSoup  class  
from bs4 import BeautifulSoup

# html_str  To parse HTML Code ( The data type is string )
#  The parser is 'html.parser', Notice the quotation marks around the parser 
soup = BeautifulSoup(html_str)

12.3 summary