Regular Expression in Python

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We can select string with some patterns.

Import library

import re

. matches any character except a newline
^a all strings starting with 'a'
a$ all strings ending with 'a'
ab+ matches 'ab', 'abb' but not 'a', 'ac'.
[bcr]at any characters within [] can be filled the space
Using \ to escape special characters
- \s : whitespace characters. \S: any except whitespace.
- \b : empty strings (only at the beginning or end of a word). \B:
cat|dog would match 'catfish' and 'hotdog' for begin and end characters
[amk] will match 'a', 'm', or `'k``
[0-9] will match any character that falls between 0 and 9
[a-z] : lowercase
[0-9]{4}: repeat the pattern [0-9] four times by writing
a{m,n} matches from m to n repetitions of 'a'.
- a{m,} matches from m to infinity repetitions of 'a'.