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[regular expression] matching grouping

2022-07-27 15:48:00 【Grapefruit tree CC】

1. Matching grouping related regular expressions

Code	function
\|	Match any expression left or right
(ab)	Use the characters in brackets as a group
`\num`	Reference group num Matching string
`(?P)`	Group aliases
(?P=name)	Quote alias as name Group matched strings

Example 1：|

demand ： In the list [“apple”, “banana”, “orange”, “pear”], matching apple and pear

import re

#  Fruit list 
fruit_list = ["apple", "banana", "orange", "pear"]

#  Traversal data 
for value in fruit_list:
    # |  Match any expression left or right 
    match_obj = re.match("apple|pear", value)
    if match_obj:
        print("%s It's what I want " % match_obj.group())
    else:
        print("%s It's not what I want " % value)

Execution results :

apple It's what I want 
banana It's not what I want 
orange It's not what I want 
pear It's what I want

Example 2：( )

demand ： Match out 163、126、qq Wait for email

import re

match_obj = re.match("[a-zA-Z0-9_]{4,20}@(163|126|qq|sina|yahoo)\.com", "[email protected]")
if match_obj:
    print(match_obj.group())
    #  Get group data 
    print(match_obj.group(1))
else:
    print(" Matching failure ")

Execution results :

[email protected]
163

demand : matching qq:10567 Data like this , extracted qq Text and qq number

import re

match_obj = re.match("(qq):([1-9]\d{4,10})", "qq:10567")

if match_obj:
    print(match_obj.group())
    #  grouping : The default is 1 A group , Multiple groups add... From left to right 1
    print(match_obj.group(1))
    #  Extract the second packet data 
    print(match_obj.group(2))
else:
    print(" Matching failure ")

Execution results :

qq
10567

Example 3：\num

demand ： Match out hh

match_obj = re.match("<[a-zA-Z1-6]+>.*</[a-zA-Z1-6]+>", "<html>hh</div>")

if match_obj:
    print(match_obj.group())
else:
    print(" Matching failure ")

match_obj = re.match("<([a-zA-Z1-6]+)>.*</\\1>", "<html>hh</html>")

if match_obj:
    print(match_obj.group())
else:
    print(" Matching failure ")

Running results ：

<html>hh</div>
<html>hh</html>

demand ： Match out www.baidu.cn

match_obj = re.match("<([a-zA-Z1-6]+)><([a-zA-Z1-6]+)>.*</\\2></\\1>", "<html><h1>www.baidu.cn</h1></html>")

if match_obj:
    print(match_obj.group())
else:
    print(" Matching failure ")

Running results ：

<html><h1>www.itcast.cn</h1></html>

Example 4：`(?P)(?P=name)`

demand ： Match out www.itcast.cn

match_obj = re.match("<(?P<name1>[a-zA-Z1-6]+)><(?P<name2>[a-zA-Z1-6]+)>.*</(?P=name2)></(?P=name1)>", "<html><h1>www.itcast.cn</h1></html>")

if match_obj:
    print(match_obj.group())
else:
    print(" Matching failure ")