{"id":3377,"date":"2021-12-10T01:19:00","date_gmt":"2021-12-10T01:19:00","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=3377"},"modified":"2021-12-10T01:28:15","modified_gmt":"2021-12-10T01:28:15","slug":"python-regex-cheat-sheet","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-regex\/python-regex-cheat-sheet\/","title":{"rendered":"Python Regex Cheat Sheet"},"content":{"rendered":"\n

This page provides a Python regex cheat sheet that you can quickly reference while working with regular expressions<\/a>.<\/p>\n\n\n\n

Character sets #<\/a><\/h2>\n\n\n\n
Pattern<\/th>Meaning<\/th><\/tr><\/thead>
\\w<\/code><\/td>Match a single word character a-z, A-Z, 0-9, and underscore (_)<\/td><\/tr>
\\d<\/code><\/td>Match a single digit 0-9<\/td><\/tr>
\\s<\/code><\/td>Match whitespace including \\t, \\n, and \\r and space character<\/td><\/tr>
.<\/code><\/td>Match any character except the newline<\/td><\/tr>
\\W<\/code><\/td>Match a character except for a word character<\/td><\/tr>
\\D<\/code><\/td>Match a character except for a digit<\/td><\/tr>
\\S<\/code><\/td>Match a single character except for a whitespace character<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Anchors #<\/a><\/h2>\n\n\n\n
Pattern<\/th>Meaning<\/th><\/tr><\/thead>
^<\/code><\/td>Match at the beginning of a string<\/td><\/tr>
$<\/code><\/td>Match at the end of a string<\/td><\/tr>
\\b<\/code><\/td>Match a position defined as a word boundary<\/td><\/tr>
\\B<\/code><\/td>Match a position that is not a word boundary<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Quantifiers #<\/a><\/h2>\n\n\n\n
Quantifiers (Greedy)<\/th>Non-greedy Quantifiers (Lazy)<\/th>Meaning<\/th><\/tr><\/thead>
*<\/code><\/td>*?<\/code><\/td>Match its preceding element zero or more times.<\/td><\/tr>
+<\/code><\/td>+?<\/code><\/td>Match its preceding element one or more times.<\/td><\/tr>
?<\/code><\/td>??<\/code><\/td>Match its preceding element zero or one time.<\/td><\/tr>
{n}<\/code><\/td>{n}?<\/code><\/td>Match its preceding element exactly\u00a0n<\/code>\u00a0times.<\/td><\/tr>
{n , }<\/code><\/td>{n,}?<\/code><\/td>Match its preceding element at least\u00a0n<\/code>\u00a0times.<\/td><\/tr>
{n , m}<\/code><\/td>{n , m}?<\/code><\/td>Match its preceding element from\u00a0n<\/code>\u00a0to\u00a0m<\/code>\u00a0times<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Sets & Ranges #<\/a><\/h2>\n\n\n\n
Pattern<\/th>Meaning<\/th><\/tr><\/thead>
[XYZ]<\/code><\/td>Match any of three elements X, Y, and Z<\/td><\/tr>
[X-Y]<\/code><\/td>Match a range from X to Y <\/td><\/tr>
^[XYZ]<\/code><\/td>Match any single element except X, Y, and Z<\/td><\/tr>
^[X-Y]<\/code><\/td>Match any single element <\/td><\/tr>
{n , }<\/code><\/td>Match its preceding element at least\u00a0n<\/code>\u00a0times.<\/td><\/tr>
{n , m}<\/code><\/td>Match its preceding element from\u00a0n<\/code>\u00a0to\u00a0m<\/code>\u00a0times<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Capturing Groups #<\/a><\/h2>\n\n\n\n
Pattern<\/th>Meaning<\/th><\/tr><\/thead>
(X)<\/code><\/td>Capture the X in the group<\/td><\/tr>
(?P<name>X)<\/code><\/td>Capture the X and assign it the name<\/td><\/tr>
\\N<\/code><\/td>Reference the capturing group #N<\/td><\/tr>
\\g<N><\/code><\/td>Reference the capturing group #N (alternative syntax)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Alternation #<\/a><\/h2>\n\n\n\n
Pattern<\/th>Meaning<\/th><\/tr><\/thead>
X | Y<\/code><\/td>Match either X or Y<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Look Around #<\/a><\/h2>\n\n\n\n
Pattern<\/th>Meaning<\/th><\/tr><\/thead>
X(?=Y)<\/code><\/td>Match X but only if it is followed by Y<\/td><\/tr>
X(?!Y)<\/code><\/td>Match X but only if it is NOT followed by Y<\/td><\/tr>
(?<=Y)X<\/code><\/code><\/td>Match X if there is Y before it<\/td><\/tr>
(?<!Y)X<\/code><\/code><\/td>Match X if there is NO Y before it<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

<\/p>\n\n\n\n

Regex functions #<\/a><\/h2>\n\n\n\n

The following table shows the regex function from the re module.<\/p>\n\n\n\n

Function<\/th>Description<\/th><\/tr><\/thead>
findall()<\/a><\/code><\/td>Return a list of matches or None<\/td><\/tr>
finditer()<\/a><\/code><\/td>Return an iterator yielding all non-overlapping matches<\/td><\/tr>
search()<\/a><\/code><\/code><\/td>Return the first match<\/td><\/tr>
fullmatch()<\/a><\/code><\/code><\/td>Return a Match object if the whole string matches a pattern<\/td><\/tr>
match()<\/a><\/code><\/td>Return the match at the beginning of a string or None<\/td><\/tr>
sub()<\/a><\/code><\/td>Return a string with matched replaced with a replacement<\/td><\/tr>
split()<\/a><\/code><\/td>Split a string at the occurrences of matches <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Regex Flags #<\/a><\/h2>\n\n\n\n
Flag<\/th>Alias<\/th>Inline Flag<\/th>Meaning<\/th><\/tr><\/thead>
re.ASCII<\/code><\/td>re.A<\/code><\/td>?m<\/code><\/td>The re.ASCII<\/code> is relevant to the byte patterns only. It makes the \\w<\/code>, \\W<\/code>,\\b<\/code>, \\B<\/code>, \\d<\/code>, \\D, and \\S<\/code> perform ASCII-only matching instead of full Unicode matching.<\/td><\/tr>
re.DEBUG<\/code><\/td>N\/A<\/td>N\/A<\/td>The re.DEBUG<\/code> shows the debug information of compiled pattern.<\/td><\/tr>
re.IGNORECASE<\/code><\/td>re.I<\/code><\/td>?i<\/code><\/td>perform case-insensitive matching. It means that the [A-Z]<\/code> will also match lowercase letters.<\/td><\/tr>
re.LOCALE<\/code><\/td>re.L<\/code><\/td>?L<\/code><\/td>The re.LOCALE<\/code> is relevant only to the byte pattern. It makes the \\w<\/code>, \\W<\/code>, \\b<\/code>, \\B<\/code> and case-sensitive matching dependent on the current locale. The re.LOCALE<\/code> is not compatible with the re.ASCII<\/code> flag.<\/td><\/tr>
re.MUTILINE<\/code><\/td>re.M<\/code><\/td>?m<\/code><\/td>The re.MULTILINE<\/code> makes the ^<\/code> matches at the beginning of a string and at the beginning of each line and $<\/code> matches at the end of a string and at the end of each line.<\/td><\/tr>
re.DOTALL<\/code><\/td>re.S<\/code><\/td>?s<\/code><\/td>By default, the dot (.<\/code>) matches any characters except a newline. The re.DOTALL<\/code> makes the dot (.<\/code>) matches all characters including a newline.<\/td><\/tr>
re.VERBOSE<\/code><\/td>re.X<\/code><\/td>?x<\/code><\/td>The re.VERBOSE<\/code> flag allows you to organize a pattern into logical sections visually and add comments.<\/td><\/tr><\/tbody><\/table><\/figure>\n
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