python-regex-chtsht.md

Python Regular Expressions Cheatsheet

Regular Expressions

Basics

Match	Regex
Any character except newline	.
The character a	a
The string ab	ab
a or b	a | b
0 or more a's	a*
Escapes a special character	\

Quantifiers

Match	Regex
0 or more	*
1 or more	+
0 or 1	?
Exactly 2	{2}
Between 2 and 5	{2, 5}
2 or more	{2,}
Up to 5	(,5}

Character Classes

Match	Regex
One character of: a, b, c, d	[ab-d]
One character except: a, b, c, d	[^ab-d]
Backspace character	[\b]
One digit	\d
One non-digit	\D
One whitespace	\s
One non-whitespace	\S
One word character	\w
One non-word character	\W

Assertions

Match	Regex
Start of string	^
Start of string, ignores m flag	\A
End of string	$
End of string, ignores m flag	\Z
Word boundary	\b
Non-word boundary	\B
Positive lookahead	(?=...)
Negative lookahead	(?!...)
Positive lookbehind	(?<=...)
Negative lookbehind	(?<!...)
Conditional	(?() | )

Groups

Match	Regex
Capturing group	(...)
Capturing group named Y	(?P<Y>...)
Non-capturing group	(?:...)
Match the Y'th captured group	\Y
Match the named group Y	(?P=Y)
Comment	(?#...)

Flags

Match	Regex
Ignore case	i
^ and $ match start and end of line	m
. matches newline as well	s
Allow spaces and comments	x
Locale character classes	L
Unicode character classes	u
Set flags within regex	(?iLmsux)

Special Characters

Match	Regex
Newline	\n
Carriage return	\r
Tab	\t
Octal character YYY	\YYY
Hexadecimal character YY	\xYY

Replacement

Match	Regex
Insert entire match	\g<0>
Insert match Y (name or number)	\g<Y>
Insert group numbered Y	\Y

strftime() and strptime() Format Codes

https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes

References

• https://www.debuggex.com/cheatsheet/regex/python