Regular expression syntax summary

Here are some basic elements of regular expressions in Python:

.

Match any character except a newline.

^

Match the start of the source string.

$

Match the end of the source string.

*

Match 0 or more repetitions of the preceding expression.

+

Match 1 or more repetitions of the preceding expression.

[…]

Match any of a set of characters. Characters may be listed individually; for example, [ace] will match the characters 'a', 'c', or 'e'. A set may also contain character ranges; for example, [0-9a-dA-D] will match any decimal digit, the lowercase characters from 'a' to 'd', or the uppercase characters from 'A' to 'D'. A set may also contain character classes such as \d or \w.

[^…]

Match any character that is not in the given set.

?

Match 0 or 1 repetitions of the preceding expression.

expr1 | expr2

Matches either expr1 or expr2.

(…)

Indicates the start and end of a group.

\number

Matches the contents of the group of the same number. Groups are numbered starting from 1.

\b

Match an empty string at the beginning or end of a word. A word is defined as a sequence of characters matched by \w.

\d

Match any decimal digit.

\s

Match any whitespace character.

\w

Match any alphanumeric character, including underscores.