Python Regex Cheat Sheet

Basic Patterns

Pattern	Description
^	Matches the beginning of a string.
$	Matches the end of a string.
.	Matches any single character except newline characters.
[...]	Matches any character listed between the square brackets.
[^...]	Matches any character not listed between the square brackets.
\d	Matches any digit, equivalent to [0-9].
\D	Matches any non-digit.
\w	Matches any word character (alphanumeric plus underscore).
\W	Matches any non-word character.
\s	Matches any whitespace character.
\S	Matches any non-whitespace character.
\b	Matches a word boundary.
\B	Matches a non-word boundary.

Quantifiers

Pattern	Description
*	Matches zero or more occurrences of the preceding element.
+	Matches one or more occurrences of the preceding element.
?	Matches zero or one occurrence of the preceding element.
{n}	Matches exactly n occurrences of the preceding element.
{n,}	Matches n or more occurrences of the preceding element.
{n,m}	Matches between n and m occurrences of the preceding element.

Groups and Lookaround

Pattern	Description
(...)	Defines a capturing group.
(?:...)	Defines a non-capturing group.
(?=...)	Positive lookahead assertion.
(?!...)	Negative lookahead assertion.
(?<=...)	Positive lookbehind assertion.
(?	Negative lookbehind assertion.

Modifiers

Modifier	Description
i	Case-insensitive matching.
m	Multiline matching, affects ^ and $.
s	Dot matches newline.
x	Extended mode. Whitespace is ignored.

Escape Sequences

Pattern	Description
\	Escapes a special character.
\t	Matches a tab character.
\n	Matches a newline character.
\r	Matches a carriage return character.
\f	Matches a form feed character.
\v	Matches a vertical tab character.
\A	Matches the start of a string.
\Z	Matches the end of a string. If the string ends with a newline, it matches just before the newline.
\z	Matches the absolute end of a string.

Special Sequences

Pattern	Description
\A	Matches only at the start of the string.
\Z	Matches only at the end of the string.
\number	Matches the contents of the group of the same number.

Flags

Flag	Description
re.ASCII	Make \w, \W, \b, \B, \d, \D, \s and \S perform ASCII-only matching.
re.DEBUG	Display debug information about the compiled expression.
re.LOCALE	Make \w, \W, \b, \B, \s, \S dependent on the current locale.
re.UNICODE	Make \w, \W, \b, \B, \d, \D, \s, \S dependent on the Unicode character properties database.

Non-capturing and Named Groups

Pattern	Description
(?:...)	Non-capturing version of regular parentheses.
(?P<name>...)	Group matches the expression and can be accessed by the name.
(?P=name)	Backreference to a named group.

Comments

Pattern	Description
(?#...)	Comment; the contents of the parentheses are simply ignored.

Conditional Matching

Pattern	Description
(?(id/name)yes-pattern|no-pattern)	Will try to match with yes-pattern if the group with given id or name exists, otherwise will try to match with no-pattern.

Greedy vs. Non-Greedy Matching

Pattern	Description
*?	Matches as few characters as possible (non-greedy version of *).
+?	Matches as few characters as possible (non-greedy version of +).
??	Matches as few characters as possible (non-greedy version of ?).
{m,n}?	Matches as few characters as possible (non-greedy version of {m,n}).

Escape Sequences for Special Characters

Pattern	Description
\	Matches a single backslash.
\^	Matches a caret (^) character.
\$	Matches a dollar ($) character.
\.	Matches a period (.) character.
\*	Matches an asterisk (*) character.
\+	Matches a plus (+) character.
\?	Matches a question mark (?) character.
\{	Matches an opening curly brace ({) character.
\}	Matches a closing curly brace (}) character.

POSIX Character Classes

Pattern	Description
[:alnum:]	Matches alphanumeric characters.
[:alpha:]	Matches alphabetic characters.
[:digit:]	Matches digits.
[:lower:]	Matches lowercase alphabetic characters.
[:upper:]	Matches uppercase alphabetic characters.
[:space:]	Matches whitespace characters.