search
HomeBackend DevelopmentPython TutorialHow to implement overlapping matching with python regular expressions

This article brings you relevant knowledge about Python. It mainly introduces how python regular expressions implement overlapping matching. It has a good reference value. Let’s take a look at it together. I hope it will help Everyone is helpful.

How to implement overlapping matching with python regular expressions

[Related recommendations: Python3 video tutorial]

Regular expressions to implement overlapping matching

import regex
string = '100101010001'
str_re = '101'
print(regex.findall(str_re, string, overlapped=True))

Ordinary re library matching can only match one '101'.

Regular expression and regular matching

Regular expression

Regular expression can be understood as an expression for filtering data, which is a limited number of atoms and metacharacters.

Atoms: Basic unit, each expression has at least one atom

Ordinary characters make up atoms

Non-printing characters make up atoms

(Characters that are not printed on the output station)

\n :Line break

\t:Tab backspace character

Common characters form atoms

\w: Match any letter, Numbers, underscores

\W: Opposite of \w

\d: Matches any decimal number

\D: Opposite of \d

\s : Matches any whitespace characters, such as spaces, newlines, indents

\S: Opposite of \s

Atomic table composed of atoms

A group of atoms forms a table, which is declared by []

The priorities of the atoms in the table are equal, but the contents only appear in order

If the atom table starts with ^, it means inversion

#普通字符组成原子
pat1 = "abcd"
 
#非打印字符组成原子
pat2 = "\n"
 
#通用字符做原子
pat3 = "\w"
 
#原子表组成原子
pat4 = "py[abc]"
#可以匹配pya,pyb,pyc,但匹配pyab等原子表重复出现的情况失败
 
#原子表开头带 ^ 表示取反
pat5 = "py[^abc]"
#第三个位置匹配除了a,b,c外的任意一个字符

Metacharacters: Characters with special meaning in regular expressions

. Matches any character, except newline characters
^ Matches the beginning of the string
$ Matches the end position of the string. When there are multiple sets of matching matches, the last set of matches in the string is returned.
* Match 0, 1, n times the previous atom [Greedy mode: match as many as possible]
? Match 0, 1 time the previous atom [Lazy mode: exact match]
Match 1, n times the previous atom
{ j } The preceding atom appears j times
{ j , } The preceding atom appears at least j times
{ j , k } The preceding atom appears at least j times and at most k times
i | j matches i or j, if i and j appear at the same time, matching the i
( ) group, restricting the combination of this group of data to be as described in (), and only returning the description in brackets The content

Pattern modifier

is the parameter at the flag position in the function, which can be changed without changing the regular expression. Its meaning is to adjust the matching results.

##re.S matches including newline characters
re.I Ignore case when matching
re.M Multi-line matching
re.L Localized identification matching
re.U according to Unicon character matching, affecting \w \W

Regular matching

Regular expressions perform fuzzy matching on strings, and one application is regular matching. Regular matching is a technology used by python crawlers to extract target information from crawled text information.

Commonly used functions for regular matching: (call the regular expression module re)

  • re.search(pat, str[, flag]) : Scan the string str and return the position of pat (the first successful match). Flag is used to control the matching method of regular expressions
  • import re
    str = 'python'
    pat = 'pytho[a-n]'
    print(re.search(pat, str))
  • re. match(pat, str[, flag]): Scan the starting position of the string str and return the position of pat (the first successful match). Flag is used to control the matching method of the regular expression [if it starts, it will not If it matches, it ends and returns none】
  • import re
    str_1 = 'hello world'
    str_2 = 'world hello'
    pat = 'world'
    print(re.match(pat, str_1))
    print(re.match(pat, str_2))
  • re.complie(pat[, flag]): Compile the regular expression pat and return the regular expression object
  • findall(str[, pos[, endpos]]): Match all, use a list to return all matched substrings in string [not just the first time], pos and endpos can be specified in Starting position in string
  • re.complie(pat).findall(str): Global matching function, matches all substrings in str that match pat, loads a list and returns the result
  • import re
    str = "hello world hello world hello world"
    pat = "hello"
    print(re.complie(pat).findall(str))
    print(re.complie(pat).findall(str, 5, 15))
  • re.sub(pat, repl, str[, count[, flag]]): Replace matching items in the string [clean data], You can use count to specify the maximum number of replacements
  • import re
    str = "400-823-823"
    pat = "-"
    #短横改空格,最大替换次数2
    str_new = re.sub(pat, " ", str, count=2)
[Related recommendations:

Python3 video tutorial]

The above is the detailed content of How to implement overlapping matching with python regular expressions. For more information, please follow other related articles on the PHP Chinese website!

Statement
This article is reproduced at:脚本之家. If there is any infringement, please contact admin@php.cn delete
What data types can be stored in a Python array?What data types can be stored in a Python array?Apr 27, 2025 am 12:11 AM

Pythonlistscanstoreanydatatype,arraymodulearraysstoreonetype,andNumPyarraysarefornumericalcomputations.1)Listsareversatilebutlessmemory-efficient.2)Arraymodulearraysarememory-efficientforhomogeneousdata.3)NumPyarraysareoptimizedforperformanceinscient

What happens if you try to store a value of the wrong data type in a Python array?What happens if you try to store a value of the wrong data type in a Python array?Apr 27, 2025 am 12:10 AM

WhenyouattempttostoreavalueofthewrongdatatypeinaPythonarray,you'llencounteraTypeError.Thisisduetothearraymodule'sstricttypeenforcement,whichrequiresallelementstobeofthesametypeasspecifiedbythetypecode.Forperformancereasons,arraysaremoreefficientthanl

Which is part of the Python standard library: lists or arrays?Which is part of the Python standard library: lists or arrays?Apr 27, 2025 am 12:03 AM

Pythonlistsarepartofthestandardlibrary,whilearraysarenot.Listsarebuilt-in,versatile,andusedforstoringcollections,whereasarraysareprovidedbythearraymoduleandlesscommonlyusedduetolimitedfunctionality.

What should you check if the script executes with the wrong Python version?What should you check if the script executes with the wrong Python version?Apr 27, 2025 am 12:01 AM

ThescriptisrunningwiththewrongPythonversionduetoincorrectdefaultinterpretersettings.Tofixthis:1)CheckthedefaultPythonversionusingpython--versionorpython3--version.2)Usevirtualenvironmentsbycreatingonewithpython3.9-mvenvmyenv,activatingit,andverifying

What are some common operations that can be performed on Python arrays?What are some common operations that can be performed on Python arrays?Apr 26, 2025 am 12:22 AM

Pythonarrayssupportvariousoperations:1)Slicingextractssubsets,2)Appending/Extendingaddselements,3)Insertingplaceselementsatspecificpositions,4)Removingdeleteselements,5)Sorting/Reversingchangesorder,and6)Listcomprehensionscreatenewlistsbasedonexistin

In what types of applications are NumPy arrays commonly used?In what types of applications are NumPy arrays commonly used?Apr 26, 2025 am 12:13 AM

NumPyarraysareessentialforapplicationsrequiringefficientnumericalcomputationsanddatamanipulation.Theyarecrucialindatascience,machinelearning,physics,engineering,andfinanceduetotheirabilitytohandlelarge-scaledataefficiently.Forexample,infinancialanaly

When would you choose to use an array over a list in Python?When would you choose to use an array over a list in Python?Apr 26, 2025 am 12:12 AM

Useanarray.arrayoveralistinPythonwhendealingwithhomogeneousdata,performance-criticalcode,orinterfacingwithCcode.1)HomogeneousData:Arrayssavememorywithtypedelements.2)Performance-CriticalCode:Arraysofferbetterperformancefornumericaloperations.3)Interf

Are all list operations supported by arrays, and vice versa? Why or why not?Are all list operations supported by arrays, and vice versa? Why or why not?Apr 26, 2025 am 12:05 AM

No,notalllistoperationsaresupportedbyarrays,andviceversa.1)Arraysdonotsupportdynamicoperationslikeappendorinsertwithoutresizing,whichimpactsperformance.2)Listsdonotguaranteeconstanttimecomplexityfordirectaccesslikearraysdo.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

MinGW - Minimalist GNU for Windows

MinGW - Minimalist GNU for Windows

This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool