Python RegEx

Python re           https://www.w3schools.com/

re

A RegEx, or Regular Expression, is a sequence of characters that forms a search pattern.

RegEx can be used to check if a string contains the specified search pattern.

Metacharacters are characters with a special meaning

CharacterDescriptionExampleTry it
[]A set of characters"[a-m]"Try it »
\Signals a special sequence (can also be used to escape special characters)"\d"Try it »
.Any character (except newline character)"he..o"Try it »
^Starts with"^hello"Try it »
$Ends with"world$"Try it »
*Zero or more occurrences"aix*"Try it »
+One or more occurrences"aix+"Try it »
{}Exactly the specified number of occurrences"al{2}"Try it »
|Either or"falls|stays"Try it »
()Capture and group


A special sequence is a \ followed by one of the characters in the list below, and has a special meaning:

CharacterDescriptionExampleTry it
\AReturns a match if the specified characters are at the beginning of the string"\AThe"Try it »
\bReturns a match where the specified characters are at the beginning or at the end of a word
(the "r" in the beginning is making sure that the string is being treated as a "raw string")
r"\bain"
r"ain\b"
Try it »
Try it »
\BReturns a match where the specified characters are present, but NOT at the beginning (or at the end) of a word
(the "r" in the beginning is making sure that the string is being treated as a "raw string")
r"\Bain"
r"ain\B"
Try it »
Try it »
\dReturns a match where the string contains digits (numbers from 0-9)"\d"Try it »
\DReturns a match where the string DOES NOT contain digits"\D"Try it »
\sReturns a match where the string contains a white space character"\s"Try it »
\SReturns a match where the string DOES NOT contain a white space character"\S"Try it »
\wReturns a match where the string contains any word characters (characters from a to Z, digits from 0-9, and the underscore _ character)"\w"Try it »
\WReturns a match where the string DOES NOT contain any word characters"\W"Try it »
\ZReturns a match if the specified characters are at the end of the string"Spain\Z"Try it »

Sets

A set is a set of characters inside a pair of square brackets [] with a special meaning:

SetDescriptionTry it
[arn]Returns a match where one of the specified characters (ar, or n) are presentTry it »
[a-n]Returns a match for any lower case character, alphabetically between a and nTry it »
[^arn]Returns a match for any character EXCEPT ar, and nTry it »
[0123]Returns a match where any of the specified digits (012, or 3) are presentTry it »
[0-9]Returns a match for any digit between 0 and 9Try it »
[0-5][0-9]Returns a match for any two-digit numbers from 00 and 59Try it »
[a-zA-Z]Returns a match for any character alphabetically between a and z, lower case OR upper caseTry it »
[+]In sets, +*.|()$,{} has no special meaning, so [+] means: return a match for any + character in the string
import re

txt = "8 times before 11:45 AM"

#Check if the string has any characters from a to z lower case, and A to Z upper case:

x = re.findall("[a-zA-Z]", txt)

print(x)

if x:
  print("Yes, there is at least one match!")
else:
  print("No match")










Python RegEx Python RegEx Reviewed by Uthid on พฤศจิกายน 24, 2563 Rating: 5

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