Reptile resolve some notes of the library BeautifulSoup

BeautifulSoup class uses

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fundamental element	Explanation
Tag	Tag, the basic information organization unit, respectively, <> and </> indicate the beginning and end
Name	Name tag, <p> </ p> name is / 'p', the format: <tag> .name
Attributes	Tag attributes, organized in the dictionary, the format: <tag> .attrs
NavigableString	Non attribute string in the tag, <> </> string in the format: <tag> .string
Comment	Note the tag part of the string, a special type Comment

The main function of the library and use BeautifulSoup

 

1. Create BeautifulSoup library objects

 

import lxml

import requests

from bs4 import BeautifulSoup

 

 

2. Select the parser

 

python standard library	BeautifulSoup(markup, "html.parser")	built-in python standard library, execution speed is moderate, strong fault tolerance documents	python2.7 and fault tolerance documents before python3.2.2 poor
lxml HTML parser	BeautifulSoup(markup, "lxml")	Fast, strong fault tolerance documents	Need to install the C language library need to install the C language library
lxml XML parser	BeautifulSoup(markup, "xml")	Speed, the only support for XML parser	You need to install the C language library
html5lib	BeautifulSoup(markup, "html5lib")	The best fault tolerance to the way the browser parses the document, document generation HTML5 format	Slow, does not rely on external expansion

 

3. traverse the document tree

.contents return all child nodes of the current node is the return type List

.children Returns all child nodes of the current node list return type is a generator object

.descendants Returns all descendant nodes of the current node list return type generator object

.parent return to the current node's father node is the return type of node Tag

.parents return to the current node's father node returns all type list generator object

.next_sibling returns the next sibling of the current node 

.previous_sibling Returns all siblings of the current node list return type generator object

.next_element return to the current node's next Tag

.previous_sibling return to a current node

All siblings after the current node returns .next_siblings

.previous_siblings return all nodes before the current node 

.string return contents of the current node labels

If the current Tag contains multiple child nodes Tag string method can not determine the contents of which node should call

.strings return multiple content need to traverse acquisition

 

4. Search Document

    1 find_all(name, attrs, recursive, text, **kwargs)

 

Parameter name

            A string transfer

            B Regular Expressions

            C transfer list

            D pass True

            E transmission method

 

keyword parameters

            

 

text parameters

            

 

5.CSS selector

 

select method

    1 Find by label name

    2 by class name Find

    3 Find by id name

    Find a combination of 4

    Find 5 properties

select the object list is returned

Gets the label of all strings use get_text ()