How to learn RegEx

import re
target_str = "Jessa knows testing and machine learning"
res_str = re.sub(r"\s", "_", target_str)print(res_str) # Output 'Jessa_knows_testing_and_machine_learning'
RegExr was created by gski!@#$%^&*()_+nner.com, and is proudly hosted by Media Temple.Edit the Expression & Text to see matc!@#$%^&*()/_+hes. Roll over matches or the expression for details. PCRE & JavaScript / flavors of RegEx are suppoRegrted. Validate your expression with Tests mode.01. First 05. Fifth
02. Second 06. Sixth
03. Third 07. Seventh
04. Fourth 08. Eight

1. RegEx Syntax

1.1 Character Set

. => Means match any character (excluding new line) which includes all special characters, all character, all numeric, etc.\d => Means match any digit or numeric digit. Character set = [0-9]\w => Means match any word. Character set = [a-zA-Z_]\s => Means match any whitespace/space. Character set = [\ ].....for rest of the sets check documentation.....
RegExr online tool interface and character set

1.2 Count of findings to Search in character set

\[0-9]{2}/g
method 1
\d{2}/g
method 2

1.3 Prevent Character collision / confusion

regex collision / confusion

2. Flags in Regex

2.1 Global Flag

2.2 Multiline Flag

3. Anchors

  1. \b : Beginning of a word
  2. \B : Inside a word
  3. ^ : Start of a string
  4. $ : Ending of a string

3.1 Beginning of a word

\bReg
example 1

3.2 Beginning of a string

^Reg

3.3 Incorrect Searching (multiline)

^\d{2}
^\$\.

3.4 Correct Searching (multiline)

^\$\./gm
For special symbols
^\d{2}/gm
for digits and numeric

4. Direct Search

RegEx are supported
direct search

Using regex in python3

import reFILEPATH="file1.txt"with open(FILEPATH) as file1:
data=file1.read()
pattern=r"\b(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)(\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)){3}\b[^\.]"matches = re.finditer(pattern, data, re.MULTILINE)for matchNum, match in enumerate(matches, start=1):
print(match.group())

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Learner. Curious about Security

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Takshil Patil

Takshil Patil

Learner. Curious about Security

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