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internal" href="#"><code class="xref py py-mod docutils literal notranslate">re</code> — Regular expression operations</a><ul> <li><a class="reference internal" href="#regular-expression-syntax">Regular Expression Syntax</a></li> <li><a class="reference internal" href="#module-contents">Module Contents</a><ul> <li><a class="reference internal" href="#flags">Flags</a></li> <li><a class="reference internal" href="#functions">Functions</a></li> <li><a class="reference internal" href="#exceptions">Exceptions</a></li> </ul> </li> <li><a class="reference internal" href="#regular-expression-objects">Regular Expression Objects</a></li> <li><a class="reference internal" href="#match-objects">Match Objects</a></li> <li><a class="reference internal" href="#regular-expression-examples">Regular Expression Examples</a><ul> <li><a class="reference internal" href="#checking-for-a-pair">Checking for a Pair</a></li> <li><a class="reference internal" href="#simulating-scanf">Simulating scanf()</a></li> <li><a class="reference internal" href="#search-vs-match">search() vs. match()</a></li> <li><a class="reference internal" href="#making-a-phonebook">Making a Phonebook</a></li> <li><a class="reference internal" href="#text-munging">Text Munging</a></li> <li><a class="reference internal" href="#finding-all-adverbs">Finding all Adverbs</a></li> <li><a class="reference internal" href="#finding-all-adverbs-and-their-positions">Finding all Adverbs and their Positions</a></li> <li><a class="reference internal" href="#raw-string-notation">Raw String Notation</a></li> <li><a class="reference internal" href="#writing-a-tokenizer">Writing a Tokenizer</a></li> </ul> </li> </ul> </li> </ul> </div> <div> <h4>Previous topic</h4> <a href="string.html" title="previous chapter"><code class="xref py py-mod docutils literal notranslate">string</code> — Common string operations</a> </div> <div> <h4>Next topic</h4> <a href="difflib.html" title="next chapter"><code class="xref py py-mod docutils literal 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Theme <select class="theme-selector" oninput="activateTheme(this.value)"> <option value="auto" selected>Auto</option> <option value="light">Light</option> <option value="dark">Dark</option> </select> </label> |</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <section id="module-re"> <h1><code class="xref py py-mod docutils literal notranslate">re</code> — Regular expression operations<a class="headerlink" href="#module-re" title="Link to this heading">¶</a></h1> Source code: <a class="extlink-source reference external" href="https://github.com/python/cpython/tree/3.13/Lib/re/">Lib/re/</a> <hr class="docutils" /> This module provides regular expression matching operations similar to those found in Perl. Both patterns and strings to be searched can be Unicode strings (<a class="reference internal" href="stdtypes.html#str" title="str"><code class="xref py py-class docutils literal notranslate">str</code></a>) as well as 8-bit strings (<a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a>). However, Unicode strings and 8-bit strings cannot be mixed: that is, you cannot match a Unicode string with a bytes pattern or vice-versa; similarly, when asking for a substitution, the replacement string must be of the same type as both the pattern and the search string. Regular expressions use the backslash character (<code class="docutils literal notranslate">'\'</code>) to indicate special forms or to allow special characters to be used without invoking their special meaning. This collides with Python’s usage of the same character for the same purpose in string literals; for example, to match a literal backslash, one might have to write <code class="docutils literal notranslate">'\\\\'</code> as the pattern string, because the regular expression must be <code class="docutils literal notranslate">\\</code>, and each backslash must be expressed as <code class="docutils literal notranslate">\\</code> inside a regular Python string literal. Also, please note that any invalid escape sequences in Python’s usage of the backslash in string literals now generate a <a class="reference internal" href="exceptions.html#SyntaxWarning" title="SyntaxWarning"><code class="xref py py-exc docutils literal notranslate">SyntaxWarning</code></a> and in the future this will become a <a class="reference internal" href="exceptions.html#SyntaxError" title="SyntaxError"><code class="xref py py-exc docutils literal notranslate">SyntaxError</code></a>. This behaviour will happen even if it is a valid escape sequence for a regular expression. The solution is to use Python’s raw string notation for regular expression patterns; backslashes are not handled in any special way in a string literal prefixed with <code class="docutils literal notranslate">'r'</code>. So <code class="docutils literal notranslate">r"\n"</code> is a two-character string containing <code class="docutils literal notranslate">'\'</code> and <code class="docutils literal notranslate">'n'</code>, while <code class="docutils literal notranslate">"\n"</code> is a one-character string containing a newline. Usually patterns will be expressed in Python code using this raw string notation. It is important to note that most regular expression operations are available as module-level functions and methods on <a class="reference internal" href="#re-objects">compiled regular expressions</a>. The functions are shortcuts that don’t require you to compile a regex object first, but miss some fine-tuning parameters. <div class="admonition seealso"> See also The third-party <a class="extlink-pypi reference external" href="https://pypi.org/project/regex/">regex</a> module, which has an API compatible with the standard library <a class="reference internal" href="#module-re" title="re: Regular expression operations."><code class="xref py py-mod docutils literal notranslate">re</code></a> module, but offers additional functionality and a more thorough Unicode support. </div> <section id="regular-expression-syntax"> <h2>Regular Expression Syntax<a class="headerlink" href="#regular-expression-syntax" title="Link to this heading">¶</a></h2> A regular expression (or RE) specifies a set of strings that matches it; the functions in this module let you check if a particular string matches a given regular expression (or if a given regular expression matches a particular string, which comes down to the same thing). Regular expressions can be concatenated to form new regular expressions; if A and B are both regular expressions, then AB is also a regular expression. In general, if a string p matches A and another string q matches B, the string pq will match AB. This holds unless A or B contain low precedence operations; boundary conditions between A and B; or have numbered group references. Thus, complex expressions can easily be constructed from simpler primitive expressions like the ones described here. For details of the theory and implementation of regular expressions, consult the Friedl book <a class="reference internal" href="#frie09" id="id1">[Frie09]</a>, or almost any textbook about compiler construction. A brief explanation of the format of regular expressions follows. For further information and a gentler presentation, consult the <a class="reference internal" href="../howto/regex.html#regex-howto">Regular Expression HOWTO</a>. Regular expressions can contain both special and ordinary characters. Most ordinary characters, like <code class="docutils literal notranslate">'A'</code>, <code class="docutils literal notranslate">'a'</code>, or <code class="docutils literal notranslate">'0'</code>, are the simplest regular expressions; they simply match themselves. You can concatenate ordinary characters, so <code class="docutils literal notranslate">last</code> matches the string <code class="docutils literal notranslate">'last'</code>. (In the rest of this section, we’ll write RE’s in <code class="docutils literal notranslate">this special style</code>, usually without quotes, and strings to be matched <code class="docutils literal notranslate">'in single quotes'</code>.) Some characters, like <code class="docutils literal notranslate">'|'</code> or <code class="docutils literal notranslate">'('</code>, are special. Special characters either stand for classes of ordinary characters, or affect how the regular expressions around them are interpreted. Repetition operators or quantifiers (<code class="docutils literal notranslate">*</code>, <code class="docutils literal notranslate">+</code>, <code class="docutils literal notranslate">?</code>, <code class="docutils literal notranslate">{m,n}</code>, etc) cannot be directly nested. This avoids ambiguity with the non-greedy modifier suffix <code class="docutils literal notranslate">?</code>, and with other modifiers in other implementations. To apply a second repetition to an inner repetition, parentheses may be used. For example, the expression <code class="docutils literal notranslate">(?:a{6})*</code> matches any multiple of six <code class="docutils literal notranslate">'a'</code> characters. The special characters are: <dl class="simple" id="index-0"> <dt><code class="docutils literal notranslate">.</code></dt><dd>(Dot.) In the default mode, this matches any character except a newline. If the <a class="reference internal" href="#re.DOTALL" title="re.DOTALL"><code class="xref py py-const docutils literal notranslate">DOTALL</code></a> flag has been specified, this matches any character including a newline. <code class="docutils literal notranslate">(?s:.)</code> matches any character regardless of flags. </dd> </dl> <dl class="simple" id="index-1"> <dt><code class="docutils literal notranslate">^</code></dt><dd>(Caret.) Matches the start of the string, and in <a class="reference internal" href="#re.MULTILINE" title="re.MULTILINE"><code class="xref py py-const docutils literal notranslate">MULTILINE</code></a> mode also matches immediately after each newline. </dd> </dl> <dl class="simple" id="index-2"> <dt><code class="docutils literal notranslate">$</code></dt><dd>Matches the end of the string or just before the newline at the end of the string, and in <a class="reference internal" href="#re.MULTILINE" title="re.MULTILINE"><code class="xref py py-const docutils literal notranslate">MULTILINE</code></a> mode also matches before a newline. <code class="docutils literal notranslate">foo</code> matches both ‘foo’ and ‘foobar’, while the regular expression <code class="docutils literal notranslate">foo$</code> matches only ‘foo’. More interestingly, searching for <code class="docutils literal notranslate">foo.$</code> in <code class="docutils literal notranslate">'foo1\nfoo2\n'</code> matches ‘foo2’ normally, but ‘foo1’ in <a class="reference internal" href="#re.MULTILINE" title="re.MULTILINE"><code class="xref py py-const docutils literal notranslate">MULTILINE</code></a> mode; searching for a single <code class="docutils literal notranslate">$</code> in <code class="docutils literal notranslate">'foo\n'</code> will find two (empty) matches: one just before the newline, and one at the end of the string. </dd> </dl> <dl class="simple" id="index-3"> <dt><code class="docutils literal notranslate">*</code></dt><dd>Causes the resulting RE to match 0 or more repetitions of the preceding RE, as many repetitions as are possible. <code class="docutils literal notranslate">ab*</code> will match ‘a’, ‘ab’, or ‘a’ followed by any number of ‘b’s. </dd> </dl> <dl class="simple" id="index-4"> <dt><code class="docutils literal notranslate">+</code></dt><dd>Causes the resulting RE to match 1 or more repetitions of the preceding RE. <code class="docutils literal notranslate">ab+</code> will match ‘a’ followed by any non-zero number of ‘b’s; it will not match just ‘a’. </dd> </dl> <dl class="simple" id="index-5"> <dt><code class="docutils literal notranslate">?</code></dt><dd>Causes the resulting RE to match 0 or 1 repetitions of the preceding RE. <code class="docutils literal notranslate">ab?</code> will match either ‘a’ or ‘ab’. </dd> </dl> <dl class="simple" id="index-6"> <dt><code class="docutils literal notranslate">*?</code>, <code class="docutils literal notranslate">+?</code>, <code class="docutils literal notranslate">??</code></dt><dd>The <code class="docutils literal notranslate">'*'</code>, <code class="docutils literal notranslate">'+'</code>, and <code class="docutils literal notranslate">'?'</code> quantifiers are all greedy; they match as much text as possible. Sometimes this behaviour isn’t desired; if the RE <code class="docutils literal notranslate"><.*></code> is matched against <code class="docutils literal notranslate">'<a> b <c>'</code>, it will match the entire string, and not just <code class="docutils literal notranslate">'<a>'</code>. Adding <code class="docutils literal notranslate">?</code> after the quantifier makes it perform the match in non-greedy or minimal fashion; as few characters as possible will be matched. Using the RE <code class="docutils literal notranslate"><.*?></code> will match only <code class="docutils literal notranslate">'<a>'</code>. </dd> </dl> <dl id="index-7"> <dt><code class="docutils literal notranslate">*+</code>, <code class="docutils literal notranslate">++</code>, <code class="docutils literal notranslate">?+</code></dt><dd>Like the <code class="docutils literal notranslate">'*'</code>, <code class="docutils literal notranslate">'+'</code>, and <code class="docutils literal notranslate">'?'</code> quantifiers, those where <code class="docutils literal notranslate">'+'</code> is appended also match as many times as possible. However, unlike the true greedy quantifiers, these do not allow back-tracking when the expression following it fails to match. These are known as possessive quantifiers. For example, <code class="docutils literal notranslate">a*a</code> will match <code class="docutils literal notranslate">'aaaa'</code> because the <code class="docutils literal notranslate">a*</code> will match all 4 <code class="docutils literal notranslate">'a'</code>s, but, when the final <code class="docutils literal notranslate">'a'</code> is encountered, the expression is backtracked so that in the end the <code class="docutils literal notranslate">a*</code> ends up matching 3 <code class="docutils literal notranslate">'a'</code>s total, and the fourth <code class="docutils literal notranslate">'a'</code> is matched by the final <code class="docutils literal notranslate">'a'</code>. However, when <code class="docutils literal notranslate">a*+a</code> is used to match <code class="docutils literal notranslate">'aaaa'</code>, the <code class="docutils literal notranslate">a*+</code> will match all 4 <code class="docutils literal notranslate">'a'</code>, but when the final <code class="docutils literal notranslate">'a'</code> fails to find any more characters to match, the expression cannot be backtracked and will thus fail to match. <code class="docutils literal notranslate">x*+</code>, <code class="docutils literal notranslate">x++</code> and <code class="docutils literal notranslate">x?+</code> are equivalent to <code class="docutils literal notranslate">(?>x*)</code>, <code class="docutils literal notranslate">(?>x+)</code> and <code class="docutils literal notranslate">(?>x?)</code> correspondingly. <div class="versionadded"> Added in version 3.11. </div> </dd> </dl> <dl id="index-8"> <dt><code class="docutils literal notranslate">{m}</code></dt><dd>Specifies that exactly m copies of the previous RE should be matched; fewer matches cause the entire RE not to match. For example, <code class="docutils literal notranslate">a{6}</code> will match exactly six <code class="docutils literal notranslate">'a'</code> characters, but not five. </dd> <dt><code class="docutils literal notranslate">{m,n}</code></dt><dd>Causes the resulting RE to match from m to n repetitions of the preceding RE, attempting to match as many repetitions as possible. For example, <code class="docutils literal notranslate">a{3,5}</code> will match from 3 to 5 <code class="docutils literal notranslate">'a'</code> characters. Omitting m specifies a lower bound of zero, and omitting n specifies an infinite upper bound. As an example, <code class="docutils literal notranslate">a{4,}b</code> will match <code class="docutils literal notranslate">'aaaab'</code> or a thousand <code class="docutils literal notranslate">'a'</code> characters followed by a <code class="docutils literal notranslate">'b'</code>, but not <code class="docutils literal notranslate">'aaab'</code>. The comma may not be omitted or the modifier would be confused with the previously described form. </dd> <dt><code class="docutils literal notranslate">{m,n}?</code></dt><dd>Causes the resulting RE to match from m to n repetitions of the preceding RE, attempting to match as few repetitions as possible. This is the non-greedy version of the previous quantifier. For example, on the 6-character string <code class="docutils literal notranslate">'aaaaaa'</code>, <code class="docutils literal notranslate">a{3,5}</code> will match 5 <code class="docutils literal notranslate">'a'</code> characters, while <code class="docutils literal notranslate">a{3,5}?</code> will only match 3 characters. </dd> <dt><code class="docutils literal notranslate">{m,n}+</code></dt><dd>Causes the resulting RE to match from m to n repetitions of the preceding RE, attempting to match as many repetitions as possible without establishing any backtracking points. This is the possessive version of the quantifier above. For example, on the 6-character string <code class="docutils literal notranslate">'aaaaaa'</code>, <code class="docutils literal notranslate">a{3,5}+aa</code> attempt to match 5 <code class="docutils literal notranslate">'a'</code> characters, then, requiring 2 more <code class="docutils literal notranslate">'a'</code>s, will need more characters than available and thus fail, while <code class="docutils literal notranslate">a{3,5}aa</code> will match with <code class="docutils literal notranslate">a{3,5}</code> capturing 5, then 4 <code class="docutils literal notranslate">'a'</code>s by backtracking and then the final 2 <code class="docutils literal notranslate">'a'</code>s are matched by the final <code class="docutils literal notranslate">aa</code> in the pattern. <code class="docutils literal notranslate">x{m,n}+</code> is equivalent to <code class="docutils literal notranslate">(?>x{m,n})</code>. <div class="versionadded"> Added in version 3.11. </div> </dd> </dl> <dl id="index-9"> <dt><code class="docutils literal notranslate">\</code></dt><dd>Either escapes special characters (permitting you to match characters like <code class="docutils literal notranslate">'*'</code>, <code class="docutils literal notranslate">'?'</code>, and so forth), or signals a special sequence; special sequences are discussed below. If you’re not using a raw string to express the pattern, remember that Python also uses the backslash as an escape sequence in string literals; if the escape sequence isn’t recognized by Python’s parser, the backslash and subsequent character are included in the resulting string. However, if Python would recognize the resulting sequence, the backslash should be repeated twice. This is complicated and hard to understand, so it’s highly recommended that you use raw strings for all but the simplest expressions. </dd> </dl> <dl id="index-10"> <dt><code class="docutils literal notranslate">[]</code></dt><dd>Used to indicate a set of characters. In a set: <ul class="simple"> <li>Characters can be listed individually, e.g. <code class="docutils literal notranslate">[amk]</code> will match <code class="docutils literal notranslate">'a'</code>, <code class="docutils literal notranslate">'m'</code>, or <code class="docutils literal notranslate">'k'</code>.</li> </ul> <ul class="simple" id="index-11"> <li>Ranges of characters can be indicated by giving two characters and separating them by a <code class="docutils literal notranslate">'-'</code>, for example <code class="docutils literal notranslate">[a-z]</code> will match any lowercase ASCII letter, <code class="docutils literal notranslate">[0-5][0-9]</code> will match all the two-digits numbers from <code class="docutils literal notranslate">00</code> to <code class="docutils literal notranslate">59</code>, and <code class="docutils literal notranslate">[0-9A-Fa-f]</code> will match any hexadecimal digit. If <code class="docutils literal notranslate">-</code> is escaped (e.g. <code class="docutils literal notranslate">[a\-z]</code>) or if it’s placed as the first or last character (e.g. <code class="docutils literal notranslate">[-a]</code> or <code class="docutils literal notranslate">[a-]</code>), it will match a literal <code class="docutils literal notranslate">'-'</code>.</li> <li>Special characters lose their special meaning inside sets. For example, <code class="docutils literal notranslate">[(+*)]</code> will match any of the literal characters <code class="docutils literal notranslate">'('</code>, <code class="docutils literal notranslate">'+'</code>, <code class="docutils literal notranslate">'*'</code>, or <code class="docutils literal notranslate">')'</code>.</li> </ul> <ul class="simple" id="index-12"> <li>Character classes such as <code class="docutils literal notranslate">\w</code> or <code class="docutils literal notranslate">\S</code> (defined below) are also accepted inside a set, although the characters they match depend on the <a class="reference internal" href="#flags">flags</a> used.</li> </ul> <ul class="simple" id="index-13"> <li>Characters that are not within a range can be matched by complementing the set. If the first character of the set is <code class="docutils literal notranslate">'^'</code>, all the characters that are not in the set will be matched. For example, <code class="docutils literal notranslate">[^5]</code> will match any character except <code class="docutils literal notranslate">'5'</code>, and <code class="docutils literal notranslate">[^^]</code> will match any character except <code class="docutils literal notranslate">'^'</code>. <code class="docutils literal notranslate">^</code> has no special meaning if it’s not the first character in the set.</li> <li>To match a literal <code class="docutils literal notranslate">']'</code> inside a set, precede it with a backslash, or place it at the beginning of the set. For example, both <code class="docutils literal notranslate">[()[\]{}]</code> and <code class="docutils literal notranslate">[]()[{}]</code> will match a right bracket, as well as left bracket, braces, and parentheses.</li> </ul> <ul class="simple"> <li>Support of nested sets and set operations as in <a class="reference external" href="https://unicode.org/reports/tr18/">Unicode Technical Standard #18</a> might be added in the future. This would change the syntax, so to facilitate this change a <a class="reference internal" href="exceptions.html#FutureWarning" title="FutureWarning"><code class="xref py py-exc docutils literal notranslate">FutureWarning</code></a> will be raised in ambiguous cases for the time being. That includes sets starting with a literal <code class="docutils literal notranslate">'['</code> or containing literal character sequences <code class="docutils literal notranslate">'--'</code>, <code class="docutils literal notranslate">'&&'</code>, <code class="docutils literal notranslate">'~~'</code>, and <code class="docutils literal notranslate">'||'</code>. To avoid a warning escape them with a backslash.</li> </ul> <div class="versionchanged"> Changed in version 3.7: <a class="reference internal" href="exceptions.html#FutureWarning" title="FutureWarning"><code class="xref py py-exc docutils literal notranslate">FutureWarning</code></a> is raised if a character set contains constructs that will change semantically in the future. </div> </dd> </dl> <dl class="simple" id="index-14"> <dt><code class="docutils literal notranslate">|</code></dt><dd><code class="docutils literal notranslate">A|B</code>, where A and B can be arbitrary REs, creates a regular expression that will match either A or B. An arbitrary number of REs can be separated by the <code class="docutils literal notranslate">'|'</code> in this way. This can be used inside groups (see below) as well. As the target string is scanned, REs separated by <code class="docutils literal notranslate">'|'</code> are tried from left to right. When one pattern completely matches, that branch is accepted. This means that once A matches, B will not be tested further, even if it would produce a longer overall match. In other words, the <code class="docutils literal notranslate">'|'</code> operator is never greedy. To match a literal <code class="docutils literal notranslate">'|'</code>, use <code class="docutils literal notranslate">\|</code>, or enclose it inside a character class, as in <code class="docutils literal notranslate">[|]</code>. </dd> </dl> <dl class="simple" id="index-15"> <dt><code class="docutils literal notranslate">(...)</code></dt><dd>Matches whatever regular expression is inside the parentheses, and indicates the start and end of a group; the contents of a group can be retrieved after a match has been performed, and can be matched later in the string with the <code class="docutils literal notranslate">\number</code> special sequence, described below. To match the literals <code class="docutils literal notranslate">'('</code> or <code class="docutils literal notranslate">')'</code>, use <code class="docutils literal notranslate">$</code> or <code class="docutils literal notranslate">$</code>, or enclose them inside a character class: <code class="docutils literal notranslate">[(]</code>, <code class="docutils literal notranslate">[)]</code>. </dd> </dl> <dl id="index-16"> <dt><code class="docutils literal notranslate">(?...)</code></dt><dd>This is an extension notation (a <code class="docutils literal notranslate">'?'</code> following a <code class="docutils literal notranslate">'('</code> is not meaningful otherwise). The first character after the <code class="docutils literal notranslate">'?'</code> determines what the meaning and further syntax of the construct is. Extensions usually do not create a new group; <code class="docutils literal notranslate">(?P<name>...)</code> is the only exception to this rule. Following are the currently supported extensions. </dd> <dt><code class="docutils literal notranslate">(?aiLmsux)</code></dt><dd>(One or more letters from the set <code class="docutils literal notranslate">'a'</code>, <code class="docutils literal notranslate">'i'</code>, <code class="docutils literal notranslate">'L'</code>, <code class="docutils literal notranslate">'m'</code>, <code class="docutils literal notranslate">'s'</code>, <code class="docutils literal notranslate">'u'</code>, <code class="docutils literal notranslate">'x'</code>.) The group matches the empty string; the letters set the corresponding flags for the entire regular expression: <ul class="simple"> <li><a class="reference internal" href="#re.A" title="re.A"><code class="xref py py-const docutils literal notranslate">re.A</code></a> (ASCII-only matching)</li> <li><a class="reference internal" href="#re.I" title="re.I"><code class="xref py py-const docutils literal notranslate">re.I</code></a> (ignore case)</li> <li><a class="reference internal" href="#re.L" title="re.L"><code class="xref py py-const docutils literal notranslate">re.L</code></a> (locale dependent)</li> <li><a class="reference internal" href="#re.M" title="re.M"><code class="xref py py-const docutils literal notranslate">re.M</code></a> (multi-line)</li> <li><a class="reference internal" href="#re.S" title="re.S"><code class="xref py py-const docutils literal notranslate">re.S</code></a> (dot matches all)</li> <li><a class="reference internal" href="#re.U" title="re.U"><code class="xref py py-const docutils literal notranslate">re.U</code></a> (Unicode matching)</li> <li><a class="reference internal" href="#re.X" title="re.X"><code class="xref py py-const docutils literal notranslate">re.X</code></a> (verbose)</li> </ul> (The flags are described in <a class="reference internal" href="#contents-of-module-re">Module Contents</a>.) This is useful if you wish to include the flags as part of the regular expression, instead of passing a flag argument to the <a class="reference internal" href="#re.compile" title="re.compile"><code class="xref py py-func docutils literal notranslate">re.compile()</code></a> function. Flags should be used first in the expression string. <div class="versionchanged"> Changed in version 3.11: This construction can only be used at the start of the expression. </div> </dd> </dl> <dl id="index-17"> <dt><code class="docutils literal notranslate">(?:...)</code></dt><dd>A non-capturing version of regular parentheses. Matches whatever regular expression is inside the parentheses, but the substring matched by the group cannot be retrieved after performing a match or referenced later in the pattern. </dd> <dt><code class="docutils literal notranslate">(?aiLmsux-imsx:...)</code></dt><dd>(Zero or more letters from the set <code class="docutils literal notranslate">'a'</code>, <code class="docutils literal notranslate">'i'</code>, <code class="docutils literal notranslate">'L'</code>, <code class="docutils literal notranslate">'m'</code>, <code class="docutils literal notranslate">'s'</code>, <code class="docutils literal notranslate">'u'</code>, <code class="docutils literal notranslate">'x'</code>, optionally followed by <code class="docutils literal notranslate">'-'</code> followed by one or more letters from the <code class="docutils literal notranslate">'i'</code>, <code class="docutils literal notranslate">'m'</code>, <code class="docutils literal notranslate">'s'</code>, <code class="docutils literal notranslate">'x'</code>.) The letters set or remove the corresponding flags for the part of the expression: <ul class="simple"> <li><a class="reference internal" href="#re.A" title="re.A"><code class="xref py py-const docutils literal notranslate">re.A</code></a> (ASCII-only matching)</li> <li><a class="reference internal" href="#re.I" title="re.I"><code class="xref py py-const docutils literal notranslate">re.I</code></a> (ignore case)</li> <li><a class="reference internal" href="#re.L" title="re.L"><code class="xref py py-const docutils literal notranslate">re.L</code></a> (locale dependent)</li> <li><a class="reference internal" href="#re.M" title="re.M"><code class="xref py py-const docutils literal notranslate">re.M</code></a> (multi-line)</li> <li><a class="reference internal" href="#re.S" title="re.S"><code class="xref py py-const docutils literal notranslate">re.S</code></a> (dot matches all)</li> <li><a class="reference internal" href="#re.U" title="re.U"><code class="xref py py-const docutils literal notranslate">re.U</code></a> (Unicode matching)</li> <li><a class="reference internal" href="#re.X" title="re.X"><code class="xref py py-const docutils literal notranslate">re.X</code></a> (verbose)</li> </ul> (The flags are described in <a class="reference internal" href="#contents-of-module-re">Module Contents</a>.) The letters <code class="docutils literal notranslate">'a'</code>, <code class="docutils literal notranslate">'L'</code> and <code class="docutils literal notranslate">'u'</code> are mutually exclusive when used as inline flags, so they can’t be combined or follow <code class="docutils literal notranslate">'-'</code>. Instead, when one of them appears in an inline group, it overrides the matching mode in the enclosing group. In Unicode patterns <code class="docutils literal notranslate">(?a:...)</code> switches to ASCII-only matching, and <code class="docutils literal notranslate">(?u:...)</code> switches to Unicode matching (default). In bytes patterns <code class="docutils literal notranslate">(?L:...)</code> switches to locale dependent matching, and <code class="docutils literal notranslate">(?a:...)</code> switches to ASCII-only matching (default). This override is only in effect for the narrow inline group, and the original matching mode is restored outside of the group. <div class="versionadded"> Added in version 3.6. </div> <div class="versionchanged"> Changed in version 3.7: The letters <code class="docutils literal notranslate">'a'</code>, <code class="docutils literal notranslate">'L'</code> and <code class="docutils literal notranslate">'u'</code> also can be used in a group. </div> </dd> <dt><code class="docutils literal notranslate">(?>...)</code></dt><dd>Attempts to match <code class="docutils literal notranslate">...</code> as if it was a separate regular expression, and if successful, continues to match the rest of the pattern following it. If the subsequent pattern fails to match, the stack can only be unwound to a point before the <code class="docutils literal notranslate">(?>...)</code> because once exited, the expression, known as an atomic group, has thrown away all stack points within itself. Thus, <code class="docutils literal notranslate">(?>.*).</code> would never match anything because first the <code class="docutils literal notranslate">.*</code> would match all characters possible, then, having nothing left to match, the final <code class="docutils literal notranslate">.</code> would fail to match. Since there are no stack points saved in the Atomic Group, and there is no stack point before it, the entire expression would thus fail to match. <div class="versionadded"> Added in version 3.11. </div> </dd> </dl> <dl id="index-18"> <dt><code class="docutils literal notranslate">(?P<name>...)</code></dt><dd>Similar to regular parentheses, but the substring matched by the group is accessible via the symbolic group name name. Group names must be valid Python identifiers, and in <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> patterns they can only contain bytes in the ASCII range. Each group name must be defined only once within a regular expression. A symbolic group is also a numbered group, just as if the group were not named. Named groups can be referenced in three contexts. If the pattern is <code class="docutils literal notranslate">(?P<quote>['"]).*?(?P=quote)</code> (i.e. matching a string quoted with either single or double quotes): <table class="docutils align-default"> <thead> <tr class="row-odd"><th class="head">Context of reference to group “quote”</th> <th class="head">Ways to reference it</th> </tr> </thead> <tbody> <tr class="row-even"><td>in the same pattern itself</td> <td><ul class="simple"> <li><code class="docutils literal notranslate">(?P=quote)</code> (as shown)</li> <li><code class="docutils literal notranslate">\1</code></li> </ul> </td> </tr> <tr class="row-odd"><td>when processing match object m</td> <td><ul class="simple"> <li><code class="docutils literal notranslate">m.group('quote')</code></li> <li><code class="docutils literal notranslate">m.end('quote')</code> (etc.)</li> </ul> </td> </tr> <tr class="row-even"><td>in a string passed to the repl argument of <code class="docutils literal notranslate">re.sub()</code></td> <td><ul class="simple"> <li><code class="docutils literal notranslate">\g<quote></code></li> <li><code class="docutils literal notranslate">\g<1></code></li> <li><code class="docutils literal notranslate">\1</code></li> </ul> </td> </tr> </tbody> </table> <div class="versionchanged"> Changed in version 3.12: In <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> patterns, group name can only contain bytes in the ASCII range (<code class="docutils literal notranslate">b'\x00'</code>-<code class="docutils literal notranslate">b'\x7f'</code>). </div> </dd> </dl> <dl class="simple" id="index-19"> <dt><code class="docutils literal notranslate">(?P=name)</code></dt><dd>A backreference to a named group; it matches whatever text was matched by the earlier group named name. </dd> </dl> <dl class="simple" id="index-20"> <dt><code class="docutils literal notranslate">(?#...)</code></dt><dd>A comment; the contents of the parentheses are simply ignored. </dd> </dl> <dl class="simple" id="index-21"> <dt><code class="docutils literal notranslate">(?=...)</code></dt><dd>Matches if <code class="docutils literal notranslate">...</code> matches next, but doesn’t consume any of the string. This is called a lookahead assertion. For example, <code class="docutils literal notranslate">Isaac (?=Asimov)</code> will match <code class="docutils literal notranslate">'Isaac '</code> only if it’s followed by <code class="docutils literal notranslate">'Asimov'</code>. </dd> </dl> <dl class="simple" id="index-22"> <dt><code class="docutils literal notranslate">(?!...)</code></dt><dd>Matches if <code class="docutils literal notranslate">...</code> doesn’t match next. This is a negative lookahead assertion. For example, <code class="docutils literal notranslate">Isaac (?!Asimov)</code> will match <code class="docutils literal notranslate">'Isaac '</code> only if it’s not followed by <code class="docutils literal notranslate">'Asimov'</code>. </dd> </dl> <dl id="index-23"> <dt><code class="docutils literal notranslate">(?<=...)</code></dt><dd>Matches if the current position in the string is preceded by a match for <code class="docutils literal notranslate">...</code> that ends at the current position. This is called a positive lookbehind assertion. <code class="docutils literal notranslate">(?<=abc)def</code> will find a match in <code class="docutils literal notranslate">'abcdef'</code>, since the lookbehind will back up 3 characters and check if the contained pattern matches. The contained pattern must only match strings of some fixed length, meaning that <code class="docutils literal notranslate">abc</code> or <code class="docutils literal notranslate">a|b</code> are allowed, but <code class="docutils literal notranslate">a*</code> and <code class="docutils literal notranslate">a{3,4}</code> are not. Note that patterns which start with positive lookbehind assertions will not match at the beginning of the string being searched; you will most likely want to use the <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-func docutils literal notranslate">search()</code></a> function rather than the <a class="reference internal" href="#re.match" title="re.match"><code class="xref py py-func docutils literal notranslate">match()</code></a> function: <div class="doctest highlight-default notranslate"><div class="highlight"><pre>>>> import re >>> m = re.search('(?<=abc)def', 'abcdef') >>> m.group(0) 'def' </pre></div> </div> This example looks for a word following a hyphen: <div class="doctest highlight-default notranslate"><div class="highlight"><pre>>>> m = re.search(r'(?<=-)\w+', 'spam-egg') >>> m.group(0) 'egg' </pre></div> </div> <div class="versionchanged"> Changed in version 3.5: Added support for group references of fixed length. </div> </dd> </dl> <dl class="simple" id="index-24"> <dt><code class="docutils literal notranslate">(?<!...)</code></dt><dd>Matches if the current position in the string is not preceded by a match for <code class="docutils literal notranslate">...</code>. This is called a negative lookbehind assertion. Similar to positive lookbehind assertions, the contained pattern must only match strings of some fixed length. Patterns which start with negative lookbehind assertions may match at the beginning of the string being searched. </dd> </dl> <dl id="index-25"> <dt><code class="docutils literal notranslate">(?(id/name)yes-pattern|no-pattern)</code></dt><dd>Will try to match with <code class="docutils literal notranslate">yes-pattern</code> if the group with given id or name exists, and with <code class="docutils literal notranslate">no-pattern</code> if it doesn’t. <code class="docutils literal notranslate">no-pattern</code> is optional and can be omitted. For example, <code class="docutils literal notranslate">(<)?(\w+@\w+(?:\.\w+)+)(?(1)>|$)</code> is a poor email matching pattern, which will match with <code class="docutils literal notranslate">'<user@host.com>'</code> as well as <code class="docutils literal notranslate">'user@host.com'</code>, but not with <code class="docutils literal notranslate">'<user@host.com'</code> nor <code class="docutils literal notranslate">'user@host.com>'</code>. <div class="versionchanged"> Changed in version 3.12: Group id can only contain ASCII digits. In <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> patterns, group name can only contain bytes in the ASCII range (<code class="docutils literal notranslate">b'\x00'</code>-<code class="docutils literal notranslate">b'\x7f'</code>). </div> </dd> </dl> The special sequences consist of <code class="docutils literal notranslate">'\'</code> and a character from the list below. If the ordinary character is not an ASCII digit or an ASCII letter, then the resulting RE will match the second character. For example, <code class="docutils literal notranslate">\$</code> matches the character <code class="docutils literal notranslate">'$'</code>. <dl class="simple" id="index-26"> <dt><code class="docutils literal notranslate">\number</code></dt><dd>Matches the contents of the group of the same number. Groups are numbered starting from 1. For example, <code class="docutils literal notranslate">(.+) \1</code> matches <code class="docutils literal notranslate">'the the'</code> or <code class="docutils literal notranslate">'55 55'</code>, but not <code class="docutils literal notranslate">'thethe'</code> (note the space after the group). This special sequence can only be used to match one of the first 99 groups. If the first digit of number is 0, or number is 3 octal digits long, it will not be interpreted as a group match, but as the character with octal value number. Inside the <code class="docutils literal notranslate">'['</code> and <code class="docutils literal notranslate">']'</code> of a character class, all numeric escapes are treated as characters. </dd> </dl> <dl class="simple" id="index-27"> <dt><code class="docutils literal notranslate">\A</code></dt><dd>Matches only at the start of the string. </dd> </dl> <dl id="index-28"> <dt><code class="docutils literal notranslate">\b</code></dt><dd>Matches the empty string, but only at the beginning or end of a word. A word is defined as a sequence of word characters. Note that formally, <code class="docutils literal notranslate">\b</code> is defined as the boundary between a <code class="docutils literal notranslate">\w</code> and a <code class="docutils literal notranslate">\W</code> character (or vice versa), or between <code class="docutils literal notranslate">\w</code> and the beginning or end of the string. This means that <code class="docutils literal notranslate">r'\bat\b'</code> matches <code class="docutils literal notranslate">'at'</code>, <code class="docutils literal notranslate">'at.'</code>, <code class="docutils literal notranslate">'(at)'</code>, and <code class="docutils literal notranslate">'as at ay'</code> but not <code class="docutils literal notranslate">'attempt'</code> or <code class="docutils literal notranslate">'atlas'</code>. The default word characters in Unicode (str) patterns are Unicode alphanumerics and the underscore, but this can be changed by using the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag. Word boundaries are determined by the current locale if the <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> flag is used. <div class="admonition note"> Note Inside a character range, <code class="docutils literal notranslate">\b</code> represents the backspace character, for compatibility with Python’s string literals. </div> </dd> </dl> <dl id="index-29"> <dt><code class="docutils literal notranslate">\B</code></dt><dd>Matches the empty string, but only when it is not at the beginning or end of a word. This means that <code class="docutils literal notranslate">r'at\B'</code> matches <code class="docutils literal notranslate">'athens'</code>, <code class="docutils literal notranslate">'atom'</code>, <code class="docutils literal notranslate">'attorney'</code>, but not <code class="docutils literal notranslate">'at'</code>, <code class="docutils literal notranslate">'at.'</code>, or <code class="docutils literal notranslate">'at!'</code>. <code class="docutils literal notranslate">\B</code> is the opposite of <code class="docutils literal notranslate">\b</code>, so word characters in Unicode (str) patterns are Unicode alphanumerics or the underscore, although this can be changed by using the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag. Word boundaries are determined by the current locale if the <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> flag is used. <div class="admonition note"> Note Note that <code class="docutils literal notranslate">\B</code> does not match an empty string, which differs from RE implementations in other programming languages such as Perl. This behavior is kept for compatibility reasons. </div> </dd> </dl> <dl id="index-30"> <dt><code class="docutils literal notranslate">\d</code></dt><dd><dl> <dt>For Unicode (str) patterns:</dt><dd>Matches any Unicode decimal digit (that is, any character in Unicode character category <a class="reference external" href="https://www.unicode.org/versions/Unicode15.0.0/ch04.pdf#G134153">[Nd]</a>). This includes <code class="docutils literal notranslate">[0-9]</code>, and also many other digit characters. Matches <code class="docutils literal notranslate">[0-9]</code> if the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used. </dd> <dt>For 8-bit (bytes) patterns:</dt><dd>Matches any decimal digit in the ASCII character set; this is equivalent to <code class="docutils literal notranslate">[0-9]</code>. </dd> </dl> </dd> </dl> <dl id="index-31"> <dt><code class="docutils literal notranslate">\D</code></dt><dd>Matches any character which is not a decimal digit. This is the opposite of <code class="docutils literal notranslate">\d</code>. Matches <code class="docutils literal notranslate">[^0-9]</code> if the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used. </dd> </dl> <dl id="index-32"> <dt><code class="docutils literal notranslate">\s</code></dt><dd><dl> <dt>For Unicode (str) patterns:</dt><dd>Matches Unicode whitespace characters (as defined by <a class="reference internal" href="stdtypes.html#str.isspace" title="str.isspace"><code class="xref py py-meth docutils literal notranslate">str.isspace()</code></a>). This includes <code class="docutils literal notranslate">[ \t\n\r\f\v]</code>, and also many other characters, for example the non-breaking spaces mandated by typography rules in many languages. Matches <code class="docutils literal notranslate">[ \t\n\r\f\v]</code> if the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used. </dd> <dt>For 8-bit (bytes) patterns:</dt><dd>Matches characters considered whitespace in the ASCII character set; this is equivalent to <code class="docutils literal notranslate">[ \t\n\r\f\v]</code>. </dd> </dl> </dd> </dl> <dl id="index-33"> <dt><code class="docutils literal notranslate">\S</code></dt><dd>Matches any character which is not a whitespace character. This is the opposite of <code class="docutils literal notranslate">\s</code>. Matches <code class="docutils literal notranslate">[^ \t\n\r\f\v]</code> if the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used. </dd> </dl> <dl id="index-34"> <dt><code class="docutils literal notranslate">\w</code></dt><dd><dl> <dt>For Unicode (str) patterns:</dt><dd>Matches Unicode word characters; this includes all Unicode alphanumeric characters (as defined by <a class="reference internal" href="stdtypes.html#str.isalnum" title="str.isalnum"><code class="xref py py-meth docutils literal notranslate">str.isalnum()</code></a>), as well as the underscore (<code class="docutils literal notranslate">_</code>). Matches <code class="docutils literal notranslate">[a-zA-Z0-9_]</code> if the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used. </dd> <dt>For 8-bit (bytes) patterns:</dt><dd>Matches characters considered alphanumeric in the ASCII character set; this is equivalent to <code class="docutils literal notranslate">[a-zA-Z0-9_]</code>. If the <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> flag is used, matches characters considered alphanumeric in the current locale and the underscore. </dd> </dl> </dd> </dl> <dl id="index-35"> <dt><code class="docutils literal notranslate">\W</code></dt><dd>Matches any character which is not a word character. This is the opposite of <code class="docutils literal notranslate">\w</code>. By default, matches non-underscore (<code class="docutils literal notranslate">_</code>) characters for which <a class="reference internal" href="stdtypes.html#str.isalnum" title="str.isalnum"><code class="xref py py-meth docutils literal notranslate">str.isalnum()</code></a> returns <code class="docutils literal notranslate">False</code>. Matches <code class="docutils literal notranslate">[^a-zA-Z0-9_]</code> if the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used. If the <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> flag is used, matches characters which are neither alphanumeric in the current locale nor the underscore. </dd> </dl> <dl class="simple" id="index-36"> <dt><code class="docutils literal notranslate">\Z</code></dt><dd>Matches only at the end of the string. </dd> </dl> Most of the <a class="reference internal" href="../reference/lexical_analysis.html#escape-sequences">escape sequences</a> supported by Python string literals are also accepted by the regular expression parser: <div class="highlight-python3 notranslate"><div class="highlight"><pre>\a \b \f \n \N \r \t \u \U \v \x \\ </pre></div> </div> (Note that <code class="docutils literal notranslate">\b</code> is used to represent word boundaries, and means “backspace” only inside character classes.) <code class="docutils literal notranslate">'\u'</code>, <code class="docutils literal notranslate">'\U'</code>, and <code class="docutils literal notranslate">'\N'</code> escape sequences are only recognized in Unicode (str) patterns. In bytes patterns they are errors. Unknown escapes of ASCII letters are reserved for future use and treated as errors. Octal escapes are included in a limited form. If the first digit is a 0, or if there are three octal digits, it is considered an octal escape. Otherwise, it is a group reference. As for string literals, octal escapes are always at most three digits in length. <div class="versionchanged"> Changed in version 3.3: The <code class="docutils literal notranslate">'\u'</code> and <code class="docutils literal notranslate">'\U'</code> escape sequences have been added. </div> <div class="versionchanged"> Changed in version 3.6: Unknown escapes consisting of <code class="docutils literal notranslate">'\'</code> and an ASCII letter now are errors. </div> <div class="versionchanged"> Changed in version 3.8: The <code class="samp docutils literal notranslate">'\N{name}'</code> escape sequence has been added. As in string literals, it expands to the named Unicode character (e.g. <code class="docutils literal notranslate">'\N{EM DASH}'</code>). </div> </section> <section id="module-contents"> <h2>Module Contents<a class="headerlink" href="#module-contents" title="Link to this heading">¶</a></h2> The module defines several functions, constants, and an exception. Some of the functions are simplified versions of the full featured methods for compiled regular expressions. Most non-trivial applications always use the compiled form. <section id="flags"> <h3>Flags<a class="headerlink" href="#flags" title="Link to this heading">¶</a></h3> <div class="versionchanged"> Changed in version 3.6: Flag constants are now instances of <a class="reference internal" href="#re.RegexFlag" title="re.RegexFlag"><code class="xref py py-class docutils literal notranslate">RegexFlag</code></a>, which is a subclass of <a class="reference internal" href="enum.html#enum.IntFlag" title="enum.IntFlag"><code class="xref py py-class docutils literal notranslate">enum.IntFlag</code></a>. </div> <dl class="py class"> <dt class="sig sig-object py" id="re.RegexFlag"> class re.RegexFlag<a class="headerlink" href="#re.RegexFlag" title="Link to this definition">¶</a></dt> <dd>An <a class="reference internal" href="enum.html#enum.IntFlag" title="enum.IntFlag"><code class="xref py py-class docutils literal notranslate">enum.IntFlag</code></a> class containing the regex options listed below. <div class="versionadded"> Added in version 3.11: - added to <code class="docutils literal notranslate">__all__</code> </div> </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.A"> re.A<a class="headerlink" href="#re.A" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.ASCII"> re.ASCII<a class="headerlink" href="#re.ASCII" title="Link to this definition">¶</a></dt> <dd>Make <code class="docutils literal notranslate">\w</code>, <code class="docutils literal notranslate">\W</code>, <code class="docutils literal notranslate">\b</code>, <code class="docutils literal notranslate">\B</code>, <code class="docutils literal notranslate">\d</code>, <code class="docutils literal notranslate">\D</code>, <code class="docutils literal notranslate">\s</code> and <code class="docutils literal notranslate">\S</code> perform ASCII-only matching instead of full Unicode matching. This is only meaningful for Unicode (str) patterns, and is ignored for bytes patterns. Corresponds to the inline flag <code class="docutils literal notranslate">(?a)</code>. <div class="admonition note"> Note The <a class="reference internal" href="#re.U" title="re.U"><code class="xref py py-const docutils literal notranslate">U</code></a> flag still exists for backward compatibility, but is redundant in Python 3 since matches are Unicode by default for <code class="docutils literal notranslate">str</code> patterns, and Unicode matching isn’t allowed for bytes patterns. <a class="reference internal" href="#re.UNICODE" title="re.UNICODE"><code class="xref py py-const docutils literal notranslate">UNICODE</code></a> and the inline flag <code class="docutils literal notranslate">(?u)</code> are similarly redundant. </div> </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.DEBUG"> re.DEBUG<a class="headerlink" href="#re.DEBUG" title="Link to this definition">¶</a></dt> <dd>Display debug information about compiled expression. No corresponding inline flag. </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.I"> re.I<a class="headerlink" href="#re.I" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.IGNORECASE"> re.IGNORECASE<a class="headerlink" href="#re.IGNORECASE" title="Link to this definition">¶</a></dt> <dd>Perform case-insensitive matching; expressions like <code class="docutils literal notranslate">[A-Z]</code> will also match lowercase letters. Full Unicode matching (such as <code class="docutils literal notranslate">Ü</code> matching <code class="docutils literal notranslate">ü</code>) also works unless the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used to disable non-ASCII matches. The current locale does not change the effect of this flag unless the <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> flag is also used. Corresponds to the inline flag <code class="docutils literal notranslate">(?i)</code>. Note that when the Unicode patterns <code class="docutils literal notranslate">[a-z]</code> or <code class="docutils literal notranslate">[A-Z]</code> are used in combination with the <a class="reference internal" href="#re.IGNORECASE" title="re.IGNORECASE"><code class="xref py py-const docutils literal notranslate">IGNORECASE</code></a> flag, they will match the 52 ASCII letters and 4 additional non-ASCII letters: ‘İ’ (U+0130, Latin capital letter I with dot above), ‘ı’ (U+0131, Latin small letter dotless i), ‘ſ’ (U+017F, Latin small letter long s) and ‘K’ (U+212A, Kelvin sign). If the <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> flag is used, only letters ‘a’ to ‘z’ and ‘A’ to ‘Z’ are matched. </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.L"> re.L<a class="headerlink" href="#re.L" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.LOCALE"> re.LOCALE<a class="headerlink" href="#re.LOCALE" title="Link to this definition">¶</a></dt> <dd>Make <code class="docutils literal notranslate">\w</code>, <code class="docutils literal notranslate">\W</code>, <code class="docutils literal notranslate">\b</code>, <code class="docutils literal notranslate">\B</code> and case-insensitive matching dependent on the current locale. This flag can be used only with bytes patterns. Corresponds to the inline flag <code class="docutils literal notranslate">(?L)</code>. <div class="admonition warning"> Warning This flag is discouraged; consider Unicode matching instead. The locale mechanism is very unreliable as it only handles one “culture” at a time and only works with 8-bit locales. Unicode matching is enabled by default for Unicode (str) patterns and it is able to handle different locales and languages. </div> <div class="versionchanged"> Changed in version 3.6: <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> can be used only with bytes patterns and is not compatible with <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a>. </div> <div class="versionchanged"> Changed in version 3.7: Compiled regular expression objects with the <a class="reference internal" href="#re.LOCALE" title="re.LOCALE"><code class="xref py py-const docutils literal notranslate">LOCALE</code></a> flag no longer depend on the locale at compile time. Only the locale at matching time affects the result of matching. </div> </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.M"> re.M<a class="headerlink" href="#re.M" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.MULTILINE"> re.MULTILINE<a class="headerlink" href="#re.MULTILINE" title="Link to this definition">¶</a></dt> <dd>When specified, the pattern character <code class="docutils literal notranslate">'^'</code> matches at the beginning of the string and at the beginning of each line (immediately following each newline); and the pattern character <code class="docutils literal notranslate">'$'</code> matches at the end of the string and at the end of each line (immediately preceding each newline). By default, <code class="docutils literal notranslate">'^'</code> matches only at the beginning of the string, and <code class="docutils literal notranslate">'$'</code> only at the end of the string and immediately before the newline (if any) at the end of the string. Corresponds to the inline flag <code class="docutils literal notranslate">(?m)</code>. </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.NOFLAG"> re.NOFLAG<a class="headerlink" href="#re.NOFLAG" title="Link to this definition">¶</a></dt> <dd>Indicates no flag being applied, the value is <code class="docutils literal notranslate">0</code>. This flag may be used as a default value for a function keyword argument or as a base value that will be conditionally ORed with other flags. Example of use as a default value: <div class="highlight-python3 notranslate"><div class="highlight"><pre>def myfunc(text, flag=re.NOFLAG): return re.match(text, flag) </pre></div> </div> <div class="versionadded"> Added in version 3.11. </div> </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.S"> re.S<a class="headerlink" href="#re.S" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.DOTALL"> re.DOTALL<a class="headerlink" href="#re.DOTALL" title="Link to this definition">¶</a></dt> <dd>Make the <code class="docutils literal notranslate">'.'</code> special character match any character at all, including a newline; without this flag, <code class="docutils literal notranslate">'.'</code> will match anything except a newline. Corresponds to the inline flag <code class="docutils literal notranslate">(?s)</code>. </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.U"> re.U<a class="headerlink" href="#re.U" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.UNICODE"> re.UNICODE<a class="headerlink" href="#re.UNICODE" title="Link to this definition">¶</a></dt> <dd>In Python 3, Unicode characters are matched by default for <code class="docutils literal notranslate">str</code> patterns. This flag is therefore redundant with no effect and is only kept for backward compatibility. See <a class="reference internal" href="#re.ASCII" title="re.ASCII"><code class="xref py py-const docutils literal notranslate">ASCII</code></a> to restrict matching to ASCII characters instead. </dd></dl> <dl class="py data"> <dt class="sig sig-object py" id="re.X"> re.X<a class="headerlink" href="#re.X" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.VERBOSE"> re.VERBOSE<a class="headerlink" href="#re.VERBOSE" title="Link to this definition">¶</a></dt> <dd>This flag allows you to write regular expressions that look nicer and are more readable by allowing you to visually separate logical sections of the pattern and add comments. Whitespace within the pattern is ignored, except when in a character class, or when preceded by an unescaped backslash, or within tokens like <code class="docutils literal notranslate">*?</code>, <code class="docutils literal notranslate">(?:</code> or <code class="docutils literal notranslate">(?P<...></code>. For example, <code class="docutils literal notranslate">(? :</code> and <code class="docutils literal notranslate">* ?</code> are not allowed. When a line contains a <code class="docutils literal notranslate">#</code> that is not in a character class and is not preceded by an unescaped backslash, all characters from the leftmost such <code class="docutils literal notranslate">#</code> through the end of the line are ignored. This means that the two following regular expression objects that match a decimal number are functionally equal: <div class="highlight-python3 notranslate"><div class="highlight"><pre>a = re.compile(r"""\d + # the integral part \. # the decimal point \d * # some fractional digits""", re.X) b = re.compile(r"\d+\.\d*") </pre></div> </div> Corresponds to the inline flag <code class="docutils literal notranslate">(?x)</code>. </dd></dl> </section> <section id="functions"> <h3>Functions<a class="headerlink" href="#functions" title="Link to this heading">¶</a></h3> <dl class="py function"> <dt class="sig sig-object py" id="re.compile"> re.compile(pattern, flags=0)<a class="headerlink" href="#re.compile" title="Link to this definition">¶</a></dt> <dd>Compile a regular expression pattern into a <a class="reference internal" href="#re-objects">regular expression object</a>, which can be used for matching using its <a class="reference internal" href="#re.Pattern.match" title="re.Pattern.match"><code class="xref py py-func docutils literal notranslate">match()</code></a>, <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-func docutils literal notranslate">search()</code></a> and other methods, described below. The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). The sequence <div class="highlight-python3 notranslate"><div class="highlight"><pre>prog = re.compile(pattern) result = prog.match(string) </pre></div> </div> is equivalent to <div class="highlight-python3 notranslate"><div class="highlight"><pre>result = re.match(pattern, string) </pre></div> </div> but using <a class="reference internal" href="#re.compile" title="re.compile"><code class="xref py py-func docutils literal notranslate">re.compile()</code></a> and saving the resulting regular expression object for reuse is more efficient when the expression will be used several times in a single program. <div class="admonition note"> Note The compiled versions of the most recent patterns passed to <a class="reference internal" href="#re.compile" title="re.compile"><code class="xref py py-func docutils literal notranslate">re.compile()</code></a> and the module-level matching functions are cached, so programs that use only a few regular expressions at a time needn’t worry about compiling regular expressions. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.search"> re.search(pattern, string, flags=0)<a class="headerlink" href="#re.search" title="Link to this definition">¶</a></dt> <dd>Scan through string looking for the first location where the regular expression pattern produces a match, and return a corresponding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a>. Return <code class="docutils literal notranslate">None</code> if no position in the string matches the pattern; note that this is different from finding a zero-length match at some point in the string. The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.match"> re.match(pattern, string, flags=0)<a class="headerlink" href="#re.match" title="Link to this definition">¶</a></dt> <dd>If zero or more characters at the beginning of string match the regular expression pattern, return a corresponding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a>. Return <code class="docutils literal notranslate">None</code> if the string does not match the pattern; note that this is different from a zero-length match. Note that even in <a class="reference internal" href="#re.MULTILINE" title="re.MULTILINE"><code class="xref py py-const docutils literal notranslate">MULTILINE</code></a> mode, <a class="reference internal" href="#re.match" title="re.match"><code class="xref py py-func docutils literal notranslate">re.match()</code></a> will only match at the beginning of the string and not at the beginning of each line. If you want to locate a match anywhere in string, use <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-func docutils literal notranslate">search()</code></a> instead (see also <a class="reference internal" href="#search-vs-match">search() vs. match()</a>). The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.fullmatch"> re.fullmatch(pattern, string, flags=0)<a class="headerlink" href="#re.fullmatch" title="Link to this definition">¶</a></dt> <dd>If the whole string matches the regular expression pattern, return a corresponding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a>. Return <code class="docutils literal notranslate">None</code> if the string does not match the pattern; note that this is different from a zero-length match. The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). <div class="versionadded"> Added in version 3.4. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.split"> re.split(pattern, string, maxsplit=0, flags=0)<a class="headerlink" href="#re.split" title="Link to this definition">¶</a></dt> <dd>Split string by the occurrences of pattern. If capturing parentheses are used in pattern, then the text of all groups in the pattern are also returned as part of the resulting list. If maxsplit is nonzero, at most maxsplit splits occur, and the remainder of the string is returned as the final element of the list. <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.split(r'\W+', 'Words, words, words.') ['Words', 'words', 'words', ''] >>> re.split(r'(\W+)', 'Words, words, words.') ['Words', ', ', 'words', ', ', 'words', '.', ''] >>> re.split(r'\W+', 'Words, words, words.', maxsplit=1) ['Words', 'words, words.'] >>> re.split('[a-f]+', '0a3B9', flags=re.IGNORECASE) ['0', '3', '9'] </pre></div> </div> If there are capturing groups in the separator and it matches at the start of the string, the result will start with an empty string. The same holds for the end of the string: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.split(r'(\W+)', '...words, words...') ['', '...', 'words', ', ', 'words', '...', ''] </pre></div> </div> That way, separator components are always found at the same relative indices within the result list. Empty matches for the pattern split the string only when not adjacent to a previous empty match. <div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> re.split(r'\b', 'Words, words, words.') ['', 'Words', ', ', 'words', ', ', 'words', '.'] >>> re.split(r'\W*', '...words...') ['', '', 'w', 'o', 'r', 'd', 's', '', ''] >>> re.split(r'(\W*)', '...words...') ['', '...', '', '', 'w', '', 'o', '', 'r', '', 'd', '', 's', '...', '', '', ''] </pre></div> </div> The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). <div class="versionchanged"> Changed in version 3.1: Added the optional flags argument. </div> <div class="versionchanged"> Changed in version 3.7: Added support of splitting on a pattern that could match an empty string. </div> <div class="deprecated"> Deprecated since version 3.13: Passing maxsplit and flags as positional arguments is deprecated. In future Python versions they will be <a class="reference internal" href="../glossary.html#keyword-only-parameter">keyword-only parameters</a>. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.findall"> re.findall(pattern, string, flags=0)<a class="headerlink" href="#re.findall" title="Link to this definition">¶</a></dt> <dd>Return all non-overlapping matches of pattern in string, as a list of strings or tuples. The string is scanned left-to-right, and matches are returned in the order found. Empty matches are included in the result. The result depends on the number of capturing groups in the pattern. If there are no groups, return a list of strings matching the whole pattern. If there is exactly one group, return a list of strings matching that group. If multiple groups are present, return a list of tuples of strings matching the groups. Non-capturing groups do not affect the form of the result. <div class="doctest highlight-default notranslate"><div class="highlight"><pre>>>> re.findall(r'\bf[a-z]*', 'which foot or hand fell fastest') ['foot', 'fell', 'fastest'] >>> re.findall(r'(\w+)=(\d+)', 'set width=20 and height=10') [('width', '20'), ('height', '10')] </pre></div> </div> The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). <div class="versionchanged"> Changed in version 3.7: Non-empty matches can now start just after a previous empty match. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.finditer"> re.finditer(pattern, string, flags=0)<a class="headerlink" href="#re.finditer" title="Link to this definition">¶</a></dt> <dd>Return an <a class="reference internal" href="../glossary.html#term-iterator">iterator</a> yielding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a> objects over all non-overlapping matches for the RE pattern in string. The string is scanned left-to-right, and matches are returned in the order found. Empty matches are included in the result. The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). <div class="versionchanged"> Changed in version 3.7: Non-empty matches can now start just after a previous empty match. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.sub"> re.sub(pattern, repl, string, count=0, flags=0)<a class="headerlink" href="#re.sub" title="Link to this definition">¶</a></dt> <dd>Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged. repl can be a string or a function; if it is a string, any backslash escapes in it are processed. That is, <code class="docutils literal notranslate">\n</code> is converted to a single newline character, <code class="docutils literal notranslate">\r</code> is converted to a carriage return, and so forth. Unknown escapes of ASCII letters are reserved for future use and treated as errors. Other unknown escapes such as <code class="docutils literal notranslate">\&</code> are left alone. Backreferences, such as <code class="docutils literal notranslate">\6</code>, are replaced with the substring matched by group 6 in the pattern. For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.sub(r'def\s+([a-zA-Z_][a-zA-Z_0-9]*)\s*$\s*$:', ... r'static PyObject*\npy_\1(void)\n{', ... 'def myfunc():') 'static PyObject*\npy_myfunc(void)\n{' </pre></div> </div> If repl is a function, it is called for every non-overlapping occurrence of pattern. The function takes a single <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a> argument, and returns the replacement string. For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> def dashrepl(matchobj): ... if matchobj.group(0) == '-': return ' ' ... else: return '-' ... >>> re.sub('-{1,2}', dashrepl, 'pro----gram-files') 'pro--gram files' >>> re.sub(r'\sAND\s', ' & ', 'Baked Beans And Spam', flags=re.IGNORECASE) 'Baked Beans & Spam' </pre></div> </div> The pattern may be a string or a <a class="reference internal" href="#re.Pattern" title="re.Pattern"><code class="xref py py-class docutils literal notranslate">Pattern</code></a>. The optional argument count is the maximum number of pattern occurrences to be replaced; count must be a non-negative integer. If omitted or zero, all occurrences will be replaced. Empty matches for the pattern are replaced only when not adjacent to a previous empty match, so <code class="docutils literal notranslate">sub('x*', '-', 'abxd')</code> returns <code class="docutils literal notranslate">'-a-b--d-'</code>. In string-type repl arguments, in addition to the character escapes and backreferences described above, <code class="docutils literal notranslate">\g<name></code> will use the substring matched by the group named <code class="docutils literal notranslate">name</code>, as defined by the <code class="docutils literal notranslate">(?P<name>...)</code> syntax. <code class="docutils literal notranslate">\g<number></code> uses the corresponding group number; <code class="docutils literal notranslate">\g<2></code> is therefore equivalent to <code class="docutils literal notranslate">\2</code>, but isn’t ambiguous in a replacement such as <code class="docutils literal notranslate">\g<2>0</code>. <code class="docutils literal notranslate">\20</code> would be interpreted as a reference to group 20, not a reference to group 2 followed by the literal character <code class="docutils literal notranslate">'0'</code>. The backreference <code class="docutils literal notranslate">\g<0></code> substitutes in the entire substring matched by the RE. The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). <div class="versionchanged"> Changed in version 3.1: Added the optional flags argument. </div> <div class="versionchanged"> Changed in version 3.5: Unmatched groups are replaced with an empty string. </div> <div class="versionchanged"> Changed in version 3.6: Unknown escapes in pattern consisting of <code class="docutils literal notranslate">'\'</code> and an ASCII letter now are errors. </div> <div class="versionchanged"> Changed in version 3.7: Unknown escapes in repl consisting of <code class="docutils literal notranslate">'\'</code> and an ASCII letter now are errors. Empty matches for the pattern are replaced when adjacent to a previous non-empty match. </div> <div class="versionchanged"> Changed in version 3.12: Group id can only contain ASCII digits. In <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate">bytes</code></a> replacement strings, group name can only contain bytes in the ASCII range (<code class="docutils literal notranslate">b'\x00'</code>-<code class="docutils literal notranslate">b'\x7f'</code>). </div> <div class="deprecated"> Deprecated since version 3.13: Passing count and flags as positional arguments is deprecated. In future Python versions they will be <a class="reference internal" href="../glossary.html#keyword-only-parameter">keyword-only parameters</a>. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.subn"> re.subn(pattern, repl, string, count=0, flags=0)<a class="headerlink" href="#re.subn" title="Link to this definition">¶</a></dt> <dd>Perform the same operation as <a class="reference internal" href="#re.sub" title="re.sub"><code class="xref py py-func docutils literal notranslate">sub()</code></a>, but return a tuple <code class="docutils literal notranslate">(new_string, number_of_subs_made)</code>. The expression’s behaviour can be modified by specifying a flags value. Values can be any of the <a class="reference internal" href="#flags">flags</a> variables, combined using bitwise OR (the <code class="docutils literal notranslate">|</code> operator). </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.escape"> re.escape(pattern)<a class="headerlink" href="#re.escape" title="Link to this definition">¶</a></dt> <dd>Escape special characters in pattern. This is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it. For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> print(re.escape('https://www.python.org')) https://www\.python\.org >>> legal_chars = string.ascii_lowercase + string.digits + "!#$%&'*+-.^_`|~:" >>> print('[%s]+' % re.escape(legal_chars)) [abcdefghijklmnopqrstuvwxyz0123456789!\#\$%\&'\*\+\-\.\^_`\|\~:]+ >>> operators = ['+', '-', '*', '/', '**'] >>> print('|'.join(map(re.escape, sorted(operators, reverse=True)))) /|\-|\+|\*\*|\* </pre></div> </div> This function must not be used for the replacement string in <a class="reference internal" href="#re.sub" title="re.sub"><code class="xref py py-func docutils literal notranslate">sub()</code></a> and <a class="reference internal" href="#re.subn" title="re.subn"><code class="xref py py-func docutils literal notranslate">subn()</code></a>, only backslashes should be escaped. For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> digits_re = r'\d+' >>> sample = '/usr/sbin/sendmail - 0 errors, 12 warnings' >>> print(re.sub(digits_re, digits_re.replace('\\', r'\\'), sample)) /usr/sbin/sendmail - \d+ errors, \d+ warnings </pre></div> </div> <div class="versionchanged"> Changed in version 3.3: The <code class="docutils literal notranslate">'_'</code> character is no longer escaped. </div> <div class="versionchanged"> Changed in version 3.7: Only characters that can have special meaning in a regular expression are escaped. As a result, <code class="docutils literal notranslate">'!'</code>, <code class="docutils literal notranslate">'"'</code>, <code class="docutils literal notranslate">'%'</code>, <code class="docutils literal notranslate">"'"</code>, <code class="docutils literal notranslate">','</code>, <code class="docutils literal notranslate">'/'</code>, <code class="docutils literal notranslate">':'</code>, <code class="docutils literal notranslate">';'</code>, <code class="docutils literal notranslate">'<'</code>, <code class="docutils literal notranslate">'='</code>, <code class="docutils literal notranslate">'>'</code>, <code class="docutils literal notranslate">'@'</code>, and <code class="docutils literal notranslate">"`"</code> are no longer escaped. </div> </dd></dl> <dl class="py function"> <dt class="sig sig-object py" id="re.purge"> re.purge()<a class="headerlink" href="#re.purge" title="Link to this definition">¶</a></dt> <dd>Clear the regular expression cache. </dd></dl> </section> <section id="exceptions"> <h3>Exceptions<a class="headerlink" href="#exceptions" title="Link to this heading">¶</a></h3> <dl class="py exception"> <dt class="sig sig-object py" id="re.PatternError"> exception re.PatternError(msg, pattern=None, pos=None)<a class="headerlink" href="#re.PatternError" title="Link to this definition">¶</a></dt> <dd>Exception raised when a string passed to one of the functions here is not a valid regular expression (for example, it might contain unmatched parentheses) or when some other error occurs during compilation or matching. It is never an error if a string contains no match for a pattern. The <code class="docutils literal notranslate">PatternError</code> instance has the following additional attributes: <dl class="py attribute"> <dt class="sig sig-object py" id="re.PatternError.msg"> msg<a class="headerlink" href="#re.PatternError.msg" title="Link to this definition">¶</a></dt> <dd>The unformatted error message. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.PatternError.pattern"> pattern<a class="headerlink" href="#re.PatternError.pattern" title="Link to this definition">¶</a></dt> <dd>The regular expression pattern. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.PatternError.pos"> pos<a class="headerlink" href="#re.PatternError.pos" title="Link to this definition">¶</a></dt> <dd>The index in pattern where compilation failed (may be <code class="docutils literal notranslate">None</code>). </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.PatternError.lineno"> lineno<a class="headerlink" href="#re.PatternError.lineno" title="Link to this definition">¶</a></dt> <dd>The line corresponding to pos (may be <code class="docutils literal notranslate">None</code>). </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.PatternError.colno"> colno<a class="headerlink" href="#re.PatternError.colno" title="Link to this definition">¶</a></dt> <dd>The column corresponding to pos (may be <code class="docutils literal notranslate">None</code>). </dd></dl> <div class="versionchanged"> Changed in version 3.5: Added additional attributes. </div> <div class="versionchanged"> Changed in version 3.13: <code class="docutils literal notranslate">PatternError</code> was originally named <code class="docutils literal notranslate">error</code>; the latter is kept as an alias for backward compatibility. </div> </dd></dl> </section> </section> <section id="regular-expression-objects"> <h2>Regular Expression Objects<a class="headerlink" href="#regular-expression-objects" title="Link to this heading">¶</a></h2> <dl class="py class"> <dt class="sig sig-object py" id="re.Pattern"> class re.Pattern<a class="headerlink" href="#re.Pattern" title="Link to this definition">¶</a></dt> <dd>Compiled regular expression object returned by <a class="reference internal" href="#re.compile" title="re.compile"><code class="xref py py-func docutils literal notranslate">re.compile()</code></a>. <div class="versionchanged"> Changed in version 3.9: <a class="reference internal" href="#re.Pattern" title="re.Pattern"><code class="xref py py-class docutils literal notranslate">re.Pattern</code></a> supports <code class="docutils literal notranslate">[]</code> to indicate a Unicode (str) or bytes pattern. See <a class="reference internal" href="stdtypes.html#types-genericalias">Generic Alias Type</a>. </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.search"> Pattern.search(string[, pos[, endpos]])<a class="headerlink" href="#re.Pattern.search" title="Link to this definition">¶</a></dt> <dd>Scan through string looking for the first location where this regular expression produces a match, and return a corresponding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a>. Return <code class="docutils literal notranslate">None</code> if no position in the string matches the pattern; note that this is different from finding a zero-length match at some point in the string. The optional second parameter pos gives an index in the string where the search is to start; it defaults to <code class="docutils literal notranslate">0</code>. This is not completely equivalent to slicing the string; the <code class="docutils literal notranslate">'^'</code> pattern character matches at the real beginning of the string and at positions just after a newline, but not necessarily at the index where the search is to start. The optional parameter endpos limits how far the string will be searched; it will be as if the string is endpos characters long, so only the characters from pos to <code class="docutils literal notranslate">endpos - 1</code> will be searched for a match. If endpos is less than pos, no match will be found; otherwise, if rx is a compiled regular expression object, <code class="docutils literal notranslate">rx.search(string, 0, 50)</code> is equivalent to <code class="docutils literal notranslate">rx.search(string[:50], 0)</code>. <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> pattern = re.compile("d") >>> pattern.search("dog") # Match at index 0 <re.Match object; span=(0, 1), match='d'> >>> pattern.search("dog", 1) # No match; search doesn't include the "d" </pre></div> </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.match"> Pattern.match(string[, pos[, endpos]])<a class="headerlink" href="#re.Pattern.match" title="Link to this definition">¶</a></dt> <dd>If zero or more characters at the beginning of string match this regular expression, return a corresponding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a>. Return <code class="docutils literal notranslate">None</code> if the string does not match the pattern; note that this is different from a zero-length match. The optional pos and endpos parameters have the same meaning as for the <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> method. <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> pattern = re.compile("o") >>> pattern.match("dog") # No match as "o" is not at the start of "dog". >>> pattern.match("dog", 1) # Match as "o" is the 2nd character of "dog". <re.Match object; span=(1, 2), match='o'> </pre></div> </div> If you want to locate a match anywhere in string, use <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> instead (see also <a class="reference internal" href="#search-vs-match">search() vs. match()</a>). </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.fullmatch"> Pattern.fullmatch(string[, pos[, endpos]])<a class="headerlink" href="#re.Pattern.fullmatch" title="Link to this definition">¶</a></dt> <dd>If the whole string matches this regular expression, return a corresponding <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a>. Return <code class="docutils literal notranslate">None</code> if the string does not match the pattern; note that this is different from a zero-length match. The optional pos and endpos parameters have the same meaning as for the <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> method. <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> pattern = re.compile("o[gh]") >>> pattern.fullmatch("dog") # No match as "o" is not at the start of "dog". >>> pattern.fullmatch("ogre") # No match as not the full string matches. >>> pattern.fullmatch("doggie", 1, 3) # Matches within given limits. <re.Match object; span=(1, 3), match='og'> </pre></div> </div> <div class="versionadded"> Added in version 3.4. </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.split"> Pattern.split(string, maxsplit=0)<a class="headerlink" href="#re.Pattern.split" title="Link to this definition">¶</a></dt> <dd>Identical to the <a class="reference internal" href="#re.split" title="re.split"><code class="xref py py-func docutils literal notranslate">split()</code></a> function, using the compiled pattern. </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.findall"> Pattern.findall(string[, pos[, endpos]])<a class="headerlink" href="#re.Pattern.findall" title="Link to this definition">¶</a></dt> <dd>Similar to the <a class="reference internal" href="#re.findall" title="re.findall"><code class="xref py py-func docutils literal notranslate">findall()</code></a> function, using the compiled pattern, but also accepts optional pos and endpos parameters that limit the search region like for <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a>. </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.finditer"> Pattern.finditer(string[, pos[, endpos]])<a class="headerlink" href="#re.Pattern.finditer" title="Link to this definition">¶</a></dt> <dd>Similar to the <a class="reference internal" href="#re.finditer" title="re.finditer"><code class="xref py py-func docutils literal notranslate">finditer()</code></a> function, using the compiled pattern, but also accepts optional pos and endpos parameters that limit the search region like for <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a>. </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.sub"> Pattern.sub(repl, string, count=0)<a class="headerlink" href="#re.Pattern.sub" title="Link to this definition">¶</a></dt> <dd>Identical to the <a class="reference internal" href="#re.sub" title="re.sub"><code class="xref py py-func docutils literal notranslate">sub()</code></a> function, using the compiled pattern. </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Pattern.subn"> Pattern.subn(repl, string, count=0)<a class="headerlink" href="#re.Pattern.subn" title="Link to this definition">¶</a></dt> <dd>Identical to the <a class="reference internal" href="#re.subn" title="re.subn"><code class="xref py py-func docutils literal notranslate">subn()</code></a> function, using the compiled pattern. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Pattern.flags"> Pattern.flags<a class="headerlink" href="#re.Pattern.flags" title="Link to this definition">¶</a></dt> <dd>The regex matching flags. This is a combination of the flags given to <a class="reference internal" href="#re.compile" title="re.compile"><code class="xref py py-func docutils literal notranslate">compile()</code></a>, any <code class="docutils literal notranslate">(?...)</code> inline flags in the pattern, and implicit flags such as <a class="reference internal" href="#re.UNICODE" title="re.UNICODE"><code class="xref py py-const docutils literal notranslate">UNICODE</code></a> if the pattern is a Unicode string. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Pattern.groups"> Pattern.groups<a class="headerlink" href="#re.Pattern.groups" title="Link to this definition">¶</a></dt> <dd>The number of capturing groups in the pattern. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Pattern.groupindex"> Pattern.groupindex<a class="headerlink" href="#re.Pattern.groupindex" title="Link to this definition">¶</a></dt> <dd>A dictionary mapping any symbolic group names defined by <code class="docutils literal notranslate">(?P<id>)</code> to group numbers. The dictionary is empty if no symbolic groups were used in the pattern. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Pattern.pattern"> Pattern.pattern<a class="headerlink" href="#re.Pattern.pattern" title="Link to this definition">¶</a></dt> <dd>The pattern string from which the pattern object was compiled. </dd></dl> <div class="versionchanged"> Changed in version 3.7: Added support of <a class="reference internal" href="copy.html#copy.copy" title="copy.copy"><code class="xref py py-func docutils literal notranslate">copy.copy()</code></a> and <a class="reference internal" href="copy.html#copy.deepcopy" title="copy.deepcopy"><code class="xref py py-func docutils literal notranslate">copy.deepcopy()</code></a>. Compiled regular expression objects are considered atomic. </div> </section> <section id="match-objects"> <h2>Match Objects<a class="headerlink" href="#match-objects" title="Link to this heading">¶</a></h2> Match objects always have a boolean value of <code class="docutils literal notranslate">True</code>. Since <a class="reference internal" href="#re.Pattern.match" title="re.Pattern.match"><code class="xref py py-meth docutils literal notranslate">match()</code></a> and <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> return <code class="docutils literal notranslate">None</code> when there is no match, you can test whether there was a match with a simple <code class="docutils literal notranslate">if</code> statement: <div class="highlight-python3 notranslate"><div class="highlight"><pre>match = re.search(pattern, string) if match: process(match) </pre></div> </div> <dl class="py class"> <dt class="sig sig-object py" id="re.Match"> class re.Match<a class="headerlink" href="#re.Match" title="Link to this definition">¶</a></dt> <dd>Match object returned by successful <code class="docutils literal notranslate">match</code>es and <code class="docutils literal notranslate">search</code>es. <div class="versionchanged"> Changed in version 3.9: <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">re.Match</code></a> supports <code class="docutils literal notranslate">[]</code> to indicate a Unicode (str) or bytes match. See <a class="reference internal" href="stdtypes.html#types-genericalias">Generic Alias Type</a>. </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.expand"> Match.expand(template)<a class="headerlink" href="#re.Match.expand" title="Link to this definition">¶</a></dt> <dd>Return the string obtained by doing backslash substitution on the template string template, as done by the <a class="reference internal" href="#re.Pattern.sub" title="re.Pattern.sub"><code class="xref py py-meth docutils literal notranslate">sub()</code></a> method. Escapes such as <code class="docutils literal notranslate">\n</code> are converted to the appropriate characters, and numeric backreferences (<code class="docutils literal notranslate">\1</code>, <code class="docutils literal notranslate">\2</code>) and named backreferences (<code class="docutils literal notranslate">\g<1></code>, <code class="docutils literal notranslate">\g<name></code>) are replaced by the contents of the corresponding group. The backreference <code class="docutils literal notranslate">\g<0></code> will be replaced by the entire match. <div class="versionchanged"> Changed in version 3.5: Unmatched groups are replaced with an empty string. </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.group"> Match.group([group1, ...])<a class="headerlink" href="#re.Match.group" title="Link to this definition">¶</a></dt> <dd>Returns one or more subgroups of the match. If there is a single argument, the result is a single string; if there are multiple arguments, the result is a tuple with one item per argument. Without arguments, group1 defaults to zero (the whole match is returned). If a groupN argument is zero, the corresponding return value is the entire matching string; if it is in the inclusive range [1..99], it is the string matching the corresponding parenthesized group. If a group number is negative or larger than the number of groups defined in the pattern, an <a class="reference internal" href="exceptions.html#IndexError" title="IndexError"><code class="xref py py-exc docutils literal notranslate">IndexError</code></a> exception is raised. If a group is contained in a part of the pattern that did not match, the corresponding result is <code class="docutils literal notranslate">None</code>. If a group is contained in a part of the pattern that matched multiple times, the last match is returned. <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist") >>> m.group(0) # The entire match 'Isaac Newton' >>> m.group(1) # The first parenthesized subgroup. 'Isaac' >>> m.group(2) # The second parenthesized subgroup. 'Newton' >>> m.group(1, 2) # Multiple arguments give us a tuple. ('Isaac', 'Newton') </pre></div> </div> If the regular expression uses the <code class="docutils literal notranslate">(?P<name>...)</code> syntax, the groupN arguments may also be strings identifying groups by their group name. If a string argument is not used as a group name in the pattern, an <a class="reference internal" href="exceptions.html#IndexError" title="IndexError"><code class="xref py py-exc docutils literal notranslate">IndexError</code></a> exception is raised. A moderately complicated example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Malcolm Reynolds") >>> m.group('first_name') 'Malcolm' >>> m.group('last_name') 'Reynolds' </pre></div> </div> Named groups can also be referred to by their index: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m.group(1) 'Malcolm' >>> m.group(2) 'Reynolds' </pre></div> </div> If a group matches multiple times, only the last match is accessible: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(..)+", "a1b2c3") # Matches 3 times. >>> m.group(1) # Returns only the last match. 'c3' </pre></div> </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.__getitem__"> Match.__getitem__(g)<a class="headerlink" href="#re.Match.__getitem__" title="Link to this definition">¶</a></dt> <dd>This is identical to <code class="docutils literal notranslate">m.group(g)</code>. This allows easier access to an individual group from a match: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(\w+) (\w+)", "Isaac Newton, physicist") >>> m[0] # The entire match 'Isaac Newton' >>> m[1] # The first parenthesized subgroup. 'Isaac' >>> m[2] # The second parenthesized subgroup. 'Newton' </pre></div> </div> Named groups are supported as well: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Isaac Newton") >>> m['first_name'] 'Isaac' >>> m['last_name'] 'Newton' </pre></div> </div> <div class="versionadded"> Added in version 3.6. </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.groups"> Match.groups(default=None)<a class="headerlink" href="#re.Match.groups" title="Link to this definition">¶</a></dt> <dd>Return a tuple containing all the subgroups of the match, from 1 up to however many groups are in the pattern. The default argument is used for groups that did not participate in the match; it defaults to <code class="docutils literal notranslate">None</code>. For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(\d+)\.(\d+)", "24.1632") >>> m.groups() ('24', '1632') </pre></div> </div> If we make the decimal place and everything after it optional, not all groups might participate in the match. These groups will default to <code class="docutils literal notranslate">None</code> unless the default argument is given: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(\d+)\.?(\d+)?", "24") >>> m.groups() # Second group defaults to None. ('24', None) >>> m.groups('0') # Now, the second group defaults to '0'. ('24', '0') </pre></div> </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.groupdict"> Match.groupdict(default=None)<a class="headerlink" href="#re.Match.groupdict" title="Link to this definition">¶</a></dt> <dd>Return a dictionary containing all the named subgroups of the match, keyed by the subgroup name. The default argument is used for groups that did not participate in the match; it defaults to <code class="docutils literal notranslate">None</code>. For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> m = re.match(r"(?P<first_name>\w+) (?P<last_name>\w+)", "Malcolm Reynolds") >>> m.groupdict() {'first_name': 'Malcolm', 'last_name': 'Reynolds'} </pre></div> </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.start"> Match.start([group])<a class="headerlink" href="#re.Match.start" title="Link to this definition">¶</a></dt> <dt class="sig sig-object py" id="re.Match.end"> Match.end([group])<a class="headerlink" href="#re.Match.end" title="Link to this definition">¶</a></dt> <dd>Return the indices of the start and end of the substring matched by group; group defaults to zero (meaning the whole matched substring). Return <code class="docutils literal notranslate">-1</code> if group exists but did not contribute to the match. For a match object m, and a group g that did contribute to the match, the substring matched by group g (equivalent to <code class="docutils literal notranslate">m.group(g)</code>) is <div class="highlight-python3 notranslate"><div class="highlight"><pre>m.string[m.start(g):m.end(g)] </pre></div> </div> Note that <code class="docutils literal notranslate">m.start(group)</code> will equal <code class="docutils literal notranslate">m.end(group)</code> if group matched a null string. For example, after <code class="docutils literal notranslate">m = re.search('b(c?)', 'cba')</code>, <code class="docutils literal notranslate">m.start(0)</code> is 1, <code class="docutils literal notranslate">m.end(0)</code> is 2, <code class="docutils literal notranslate">m.start(1)</code> and <code class="docutils literal notranslate">m.end(1)</code> are both 2, and <code class="docutils literal notranslate">m.start(2)</code> raises an <a class="reference internal" href="exceptions.html#IndexError" title="IndexError"><code class="xref py py-exc docutils literal notranslate">IndexError</code></a> exception. An example that will remove remove_this from email addresses: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> email = "tony@tiremove_thisger.net" >>> m = re.search("remove_this", email) >>> email[:m.start()] + email[m.end():] 'tony@tiger.net' </pre></div> </div> </dd></dl> <dl class="py method"> <dt class="sig sig-object py" id="re.Match.span"> Match.span([group])<a class="headerlink" href="#re.Match.span" title="Link to this definition">¶</a></dt> <dd>For a match m, return the 2-tuple <code class="docutils literal notranslate">(m.start(group), m.end(group))</code>. Note that if group did not contribute to the match, this is <code class="docutils literal notranslate">(-1, -1)</code>. group defaults to zero, the entire match. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Match.pos"> Match.pos<a class="headerlink" href="#re.Match.pos" title="Link to this definition">¶</a></dt> <dd>The value of pos which was passed to the <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> or <a class="reference internal" href="#re.Pattern.match" title="re.Pattern.match"><code class="xref py py-meth docutils literal notranslate">match()</code></a> method of a <a class="reference internal" href="#re-objects">regex object</a>. This is the index into the string at which the RE engine started looking for a match. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Match.endpos"> Match.endpos<a class="headerlink" href="#re.Match.endpos" title="Link to this definition">¶</a></dt> <dd>The value of endpos which was passed to the <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> or <a class="reference internal" href="#re.Pattern.match" title="re.Pattern.match"><code class="xref py py-meth docutils literal notranslate">match()</code></a> method of a <a class="reference internal" href="#re-objects">regex object</a>. This is the index into the string beyond which the RE engine will not go. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Match.lastindex"> Match.lastindex<a class="headerlink" href="#re.Match.lastindex" title="Link to this definition">¶</a></dt> <dd>The integer index of the last matched capturing group, or <code class="docutils literal notranslate">None</code> if no group was matched at all. For example, the expressions <code class="docutils literal notranslate">(a)b</code>, <code class="docutils literal notranslate">((a)(b))</code>, and <code class="docutils literal notranslate">((ab))</code> will have <code class="docutils literal notranslate">lastindex == 1</code> if applied to the string <code class="docutils literal notranslate">'ab'</code>, while the expression <code class="docutils literal notranslate">(a)(b)</code> will have <code class="docutils literal notranslate">lastindex == 2</code>, if applied to the same string. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Match.lastgroup"> Match.lastgroup<a class="headerlink" href="#re.Match.lastgroup" title="Link to this definition">¶</a></dt> <dd>The name of the last matched capturing group, or <code class="docutils literal notranslate">None</code> if the group didn’t have a name, or if no group was matched at all. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Match.re"> Match.re<a class="headerlink" href="#re.Match.re" title="Link to this definition">¶</a></dt> <dd>The <a class="reference internal" href="#re-objects">regular expression object</a> whose <a class="reference internal" href="#re.Pattern.match" title="re.Pattern.match"><code class="xref py py-meth docutils literal notranslate">match()</code></a> or <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a> method produced this match instance. </dd></dl> <dl class="py attribute"> <dt class="sig sig-object py" id="re.Match.string"> Match.string<a class="headerlink" href="#re.Match.string" title="Link to this definition">¶</a></dt> <dd>The string passed to <a class="reference internal" href="#re.Pattern.match" title="re.Pattern.match"><code class="xref py py-meth docutils literal notranslate">match()</code></a> or <a class="reference internal" href="#re.Pattern.search" title="re.Pattern.search"><code class="xref py py-meth docutils literal notranslate">search()</code></a>. </dd></dl> <div class="versionchanged"> Changed in version 3.7: Added support of <a class="reference internal" href="copy.html#copy.copy" title="copy.copy"><code class="xref py py-func docutils literal notranslate">copy.copy()</code></a> and <a class="reference internal" href="copy.html#copy.deepcopy" title="copy.deepcopy"><code class="xref py py-func docutils literal notranslate">copy.deepcopy()</code></a>. Match objects are considered atomic. </div> </section> <section id="regular-expression-examples"> <h2>Regular Expression Examples<a class="headerlink" href="#regular-expression-examples" title="Link to this heading">¶</a></h2> <section id="checking-for-a-pair"> <h3>Checking for a Pair<a class="headerlink" href="#checking-for-a-pair" title="Link to this heading">¶</a></h3> In this example, we’ll use the following helper function to display match objects a little more gracefully: <div class="highlight-python3 notranslate"><div class="highlight"><pre>def displaymatch(match): if match is None: return None return '<Match: %r, groups=%r>' % (match.group(), match.groups()) </pre></div> </div> Suppose you are writing a poker program where a player’s hand is represented as a 5-character string with each character representing a card, “a” for ace, “k” for king, “q” for queen, “j” for jack, “t” for 10, and “2” through “9” representing the card with that value. To see if a given string is a valid hand, one could do the following: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> valid = re.compile(r"^[a2-9tjqk]{5}$") >>> displaymatch(valid.match("akt5q")) # Valid. "<Match: 'akt5q', groups=()>" >>> displaymatch(valid.match("akt5e")) # Invalid. >>> displaymatch(valid.match("akt")) # Invalid. >>> displaymatch(valid.match("727ak")) # Valid. "<Match: '727ak', groups=()>" </pre></div> </div> That last hand, <code class="docutils literal notranslate">"727ak"</code>, contained a pair, or two of the same valued cards. To match this with a regular expression, one could use backreferences as such: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> pair = re.compile(r".*(.).*\1") >>> displaymatch(pair.match("717ak")) # Pair of 7s. "<Match: '717', groups=('7',)>" >>> displaymatch(pair.match("718ak")) # No pairs. >>> displaymatch(pair.match("354aa")) # Pair of aces. "<Match: '354aa', groups=('a',)>" </pre></div> </div> To find out what card the pair consists of, one could use the <a class="reference internal" href="#re.Match.group" title="re.Match.group"><code class="xref py py-meth docutils literal notranslate">group()</code></a> method of the match object in the following manner: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> pair = re.compile(r".*(.).*\1") >>> pair.match("717ak").group(1) '7' # Error because re.match() returns None, which doesn't have a group() method: >>> pair.match("718ak").group(1) Traceback (most recent call last): File "<pyshell#23>", line 1, in <module> re.match(r".*(.).*\1", "718ak").group(1) AttributeError: 'NoneType' object has no attribute 'group' >>> pair.match("354aa").group(1) 'a' </pre></div> </div> </section> <section id="simulating-scanf"> <h3>Simulating scanf()<a class="headerlink" href="#simulating-scanf" title="Link to this heading">¶</a></h3> Python does not currently have an equivalent to <code class="xref c c-func docutils literal notranslate">scanf()</code>. Regular expressions are generally more powerful, though also more verbose, than <code class="xref c c-func docutils literal notranslate">scanf()</code> format strings. The table below offers some more-or-less equivalent mappings between <code class="xref c c-func docutils literal notranslate">scanf()</code> format tokens and regular expressions. <table class="docutils align-default"> <thead> <tr class="row-odd"><th class="head"><code class="xref c c-func docutils literal notranslate">scanf()</code> Token</th> <th class="head">Regular Expression</th> </tr> </thead> <tbody> <tr class="row-even"><td><code class="docutils literal notranslate">%c</code></td> <td><code class="docutils literal notranslate">.</code></td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate">%5c</code></td> <td><code class="docutils literal notranslate">.{5}</code></td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate">%d</code></td> <td><code class="docutils literal notranslate">[-+]?\d+</code></td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate">%e</code>, <code class="docutils literal notranslate">%E</code>, <code class="docutils literal notranslate">%f</code>, <code class="docutils literal notranslate">%g</code></td> <td><code class="docutils literal notranslate">[-+]?(\d+(\.\d*)?|\.\d+)([eE][-+]?\d+)?</code></td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate">%i</code></td> <td><code class="docutils literal notranslate">[-+]?(0[xX][\dA-Fa-f]+|0[0-7]*|\d+)</code></td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate">%o</code></td> <td><code class="docutils literal notranslate">[-+]?[0-7]+</code></td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate">%s</code></td> <td><code class="docutils literal notranslate">\S+</code></td> </tr> <tr class="row-odd"><td><code class="docutils literal notranslate">%u</code></td> <td><code class="docutils literal notranslate">\d+</code></td> </tr> <tr class="row-even"><td><code class="docutils literal notranslate">%x</code>, <code class="docutils literal notranslate">%X</code></td> <td><code class="docutils literal notranslate">[-+]?(0[xX])?[\dA-Fa-f]+</code></td> </tr> </tbody> </table> To extract the filename and numbers from a string like <div class="highlight-python3 notranslate"><div class="highlight"><pre>/usr/sbin/sendmail - 0 errors, 4 warnings </pre></div> </div> you would use a <code class="xref c c-func docutils literal notranslate">scanf()</code> format like <div class="highlight-python3 notranslate"><div class="highlight"><pre>%s - %d errors, %d warnings </pre></div> </div> The equivalent regular expression would be <div class="highlight-python3 notranslate"><div class="highlight"><pre>(\S+) - (\d+) errors, (\d+) warnings </pre></div> </div> </section> <section id="search-vs-match"> <h3>search() vs. match()<a class="headerlink" href="#search-vs-match" title="Link to this heading">¶</a></h3> Python offers different primitive operations based on regular expressions: <ul class="simple"> <li><a class="reference internal" href="#re.match" title="re.match"><code class="xref py py-func docutils literal notranslate">re.match()</code></a> checks for a match only at the beginning of the string</li> <li><a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-func docutils literal notranslate">re.search()</code></a> checks for a match anywhere in the string (this is what Perl does by default)</li> <li><a class="reference internal" href="#re.fullmatch" title="re.fullmatch"><code class="xref py py-func docutils literal notranslate">re.fullmatch()</code></a> checks for entire string to be a match</li> </ul> For example: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.match("c", "abcdef") # No match >>> re.search("c", "abcdef") # Match <re.Match object; span=(2, 3), match='c'> >>> re.fullmatch("p.*n", "python") # Match <re.Match object; span=(0, 6), match='python'> >>> re.fullmatch("r.*n", "python") # No match </pre></div> </div> Regular expressions beginning with <code class="docutils literal notranslate">'^'</code> can be used with <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-func docutils literal notranslate">search()</code></a> to restrict the match at the beginning of the string: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.match("c", "abcdef") # No match >>> re.search("^c", "abcdef") # No match >>> re.search("^a", "abcdef") # Match <re.Match object; span=(0, 1), match='a'> </pre></div> </div> Note however that in <a class="reference internal" href="#re.MULTILINE" title="re.MULTILINE"><code class="xref py py-const docutils literal notranslate">MULTILINE</code></a> mode <a class="reference internal" href="#re.match" title="re.match"><code class="xref py py-func docutils literal notranslate">match()</code></a> only matches at the beginning of the string, whereas using <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-func docutils literal notranslate">search()</code></a> with a regular expression beginning with <code class="docutils literal notranslate">'^'</code> will match at the beginning of each line. <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.match("X", "A\nB\nX", re.MULTILINE) # No match >>> re.search("^X", "A\nB\nX", re.MULTILINE) # Match <re.Match object; span=(4, 5), match='X'> </pre></div> </div> </section> <section id="making-a-phonebook"> <h3>Making a Phonebook<a class="headerlink" href="#making-a-phonebook" title="Link to this heading">¶</a></h3> <a class="reference internal" href="#re.split" title="re.split"><code class="xref py py-func docutils literal notranslate">split()</code></a> splits a string into a list delimited by the passed pattern. The method is invaluable for converting textual data into data structures that can be easily read and modified by Python as demonstrated in the following example that creates a phonebook. First, here is the input. Normally it may come from a file, here we are using triple-quoted string syntax <div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> text = """Ross McFluff: 834.345.1254 155 Elm Street ... ... Ronald Heathmore: 892.345.3428 436 Finley Avenue ... Frank Burger: 925.541.7625 662 South Dogwood Way ... ... ... Heather Albrecht: 548.326.4584 919 Park Place""" </pre></div> </div> The entries are separated by one or more newlines. Now we convert the string into a list with each nonempty line having its own entry: <div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> entries = re.split("\n+", text) >>> entries ['Ross McFluff: 834.345.1254 155 Elm Street', 'Ronald Heathmore: 892.345.3428 436 Finley Avenue', 'Frank Burger: 925.541.7625 662 South Dogwood Way', 'Heather Albrecht: 548.326.4584 919 Park Place'] </pre></div> </div> Finally, split each entry into a list with first name, last name, telephone number, and address. We use the <code class="docutils literal notranslate">maxsplit</code> parameter of <a class="reference internal" href="#re.split" title="re.split"><code class="xref py py-func docutils literal notranslate">split()</code></a> because the address has spaces, our splitting pattern, in it: <div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> [re.split(":? ", entry, maxsplit=3) for entry in entries] [['Ross', 'McFluff', '834.345.1254', '155 Elm Street'], ['Ronald', 'Heathmore', '892.345.3428', '436 Finley Avenue'], ['Frank', 'Burger', '925.541.7625', '662 South Dogwood Way'], ['Heather', 'Albrecht', '548.326.4584', '919 Park Place']] </pre></div> </div> The <code class="docutils literal notranslate">:?</code> pattern matches the colon after the last name, so that it does not occur in the result list. With a <code class="docutils literal notranslate">maxsplit</code> of <code class="docutils literal notranslate">4</code>, we could separate the house number from the street name: <div class="highlight-pycon notranslate"><div class="highlight"><pre>>>> [re.split(":? ", entry, maxsplit=4) for entry in entries] [['Ross', 'McFluff', '834.345.1254', '155', 'Elm Street'], ['Ronald', 'Heathmore', '892.345.3428', '436', 'Finley Avenue'], ['Frank', 'Burger', '925.541.7625', '662', 'South Dogwood Way'], ['Heather', 'Albrecht', '548.326.4584', '919', 'Park Place']] </pre></div> </div> </section> <section id="text-munging"> <h3>Text Munging<a class="headerlink" href="#text-munging" title="Link to this heading">¶</a></h3> <a class="reference internal" href="#re.sub" title="re.sub"><code class="xref py py-func docutils literal notranslate">sub()</code></a> replaces every occurrence of a pattern with a string or the result of a function. This example demonstrates using <a class="reference internal" href="#re.sub" title="re.sub"><code class="xref py py-func docutils literal notranslate">sub()</code></a> with a function to “munge” text, or randomize the order of all the characters in each word of a sentence except for the first and last characters: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> def repl(m): ... inner_word = list(m.group(2)) ... random.shuffle(inner_word) ... return m.group(1) + "".join(inner_word) + m.group(3) ... >>> text = "Professor Abdolmalek, please report your absences promptly." >>> re.sub(r"(\w)(\w+)(\w)", repl, text) 'Poefsrosr Aealmlobdk, pslaee reorpt your abnseces plmrptoy.' >>> re.sub(r"(\w)(\w+)(\w)", repl, text) 'Pofsroser Aodlambelk, plasee reoprt yuor asnebces potlmrpy.' </pre></div> </div> </section> <section id="finding-all-adverbs"> <h3>Finding all Adverbs<a class="headerlink" href="#finding-all-adverbs" title="Link to this heading">¶</a></h3> <a class="reference internal" href="#re.findall" title="re.findall"><code class="xref py py-func docutils literal notranslate">findall()</code></a> matches all occurrences of a pattern, not just the first one as <a class="reference internal" href="#re.search" title="re.search"><code class="xref py py-func docutils literal notranslate">search()</code></a> does. For example, if a writer wanted to find all of the adverbs in some text, they might use <a class="reference internal" href="#re.findall" title="re.findall"><code class="xref py py-func docutils literal notranslate">findall()</code></a> in the following manner: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> text = "He was carefully disguised but captured quickly by police." >>> re.findall(r"\w+ly\b", text) ['carefully', 'quickly'] </pre></div> </div> </section> <section id="finding-all-adverbs-and-their-positions"> <h3>Finding all Adverbs and their Positions<a class="headerlink" href="#finding-all-adverbs-and-their-positions" title="Link to this heading">¶</a></h3> If one wants more information about all matches of a pattern than the matched text, <a class="reference internal" href="#re.finditer" title="re.finditer"><code class="xref py py-func docutils literal notranslate">finditer()</code></a> is useful as it provides <a class="reference internal" href="#re.Match" title="re.Match"><code class="xref py py-class docutils literal notranslate">Match</code></a> objects instead of strings. Continuing with the previous example, if a writer wanted to find all of the adverbs and their positions in some text, they would use <a class="reference internal" href="#re.finditer" title="re.finditer"><code class="xref py py-func docutils literal notranslate">finditer()</code></a> in the following manner: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> text = "He was carefully disguised but captured quickly by police." >>> for m in re.finditer(r"\w+ly\b", text): ... print('%02d-%02d: %s' % (m.start(), m.end(), m.group(0))) 07-16: carefully 40-47: quickly </pre></div> </div> </section> <section id="raw-string-notation"> <h3>Raw String Notation<a class="headerlink" href="#raw-string-notation" title="Link to this heading">¶</a></h3> Raw string notation (<code class="docutils literal notranslate">r"text"</code>) keeps regular expressions sane. Without it, every backslash (<code class="docutils literal notranslate">'\'</code>) in a regular expression would have to be prefixed with another one to escape it. For example, the two following lines of code are functionally identical: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.match(r"\W(.)\1\W", " ff ") <re.Match object; span=(0, 4), match=' ff '> >>> re.match("\\W(.)\\1\\W", " ff ") <re.Match object; span=(0, 4), match=' ff '> </pre></div> </div> When one wants to match a literal backslash, it must be escaped in the regular expression. With raw string notation, this means <code class="docutils literal notranslate">r"\\"</code>. Without raw string notation, one must use <code class="docutils literal notranslate">"\\\\"</code>, making the following lines of code functionally identical: <div class="highlight-python3 notranslate"><div class="highlight"><pre>>>> re.match(r"\\", r"\\") <re.Match object; span=(0, 1), match='\\'> >>> re.match("\\\\", r"\\") <re.Match object; span=(0, 1), match='\\'> </pre></div> </div> </section> <section id="writing-a-tokenizer"> <h3>Writing a Tokenizer<a class="headerlink" href="#writing-a-tokenizer" title="Link to this heading">¶</a></h3> A <a class="reference external" href="https://en.wikipedia.org/wiki/Lexical_analysis">tokenizer or scanner</a> analyzes a string to categorize groups of characters. This is a useful first step in writing a compiler or interpreter. The text categories are specified with regular expressions. The technique is to combine those into a single master regular expression and to loop over successive matches: <div class="highlight-python3 notranslate"><div class="highlight"><pre>from typing import NamedTuple import re class Token(NamedTuple): type: str value: str line: int column: int def tokenize(code): keywords = {'IF', 'THEN', 'ENDIF', 'FOR', 'NEXT', 'GOSUB', 'RETURN'} token_specification = [ ('NUMBER', r'\d+(\.\d*)?'), # Integer or decimal number ('ASSIGN', r':='), # Assignment operator ('END', r';'), # Statement terminator ('ID', r'[A-Za-z]+'), # Identifiers ('OP', r'[+\-*/]'), # Arithmetic operators ('NEWLINE', r'\n'), # Line endings ('SKIP', r'[ \t]+'), # Skip over spaces and tabs ('MISMATCH', r'.'), # Any other character ] tok_regex = '|'.join('(?P<%s>%s)' % pair for pair in token_specification) line_num = 1 line_start = 0 for mo in re.finditer(tok_regex, code): kind = mo.lastgroup value = mo.group() column = mo.start() - line_start if kind == 'NUMBER': value = float(value) if '.' in value else int(value) elif kind == 'ID' and value in keywords: kind = value elif kind == 'NEWLINE': line_start = mo.end() line_num += 1 continue elif kind == 'SKIP': continue elif kind == 'MISMATCH': raise RuntimeError(f'{value!r} unexpected on line {line_num}') yield Token(kind, value, line_num, column) statements = ''' IF quantity THEN total := total + price * quantity; tax := price * 0.05; ENDIF; ''' for token in tokenize(statements): print(token) </pre></div> </div> The tokenizer produces the following output: <div class="highlight-python3 notranslate"><div class="highlight"><pre>Token(type='IF', value='IF', line=2, column=4) Token(type='ID', value='quantity', line=2, column=7) Token(type='THEN', value='THEN', line=2, column=16) Token(type='ID', value='total', line=3, column=8) Token(type='ASSIGN', value=':=', line=3, column=14) Token(type='ID', value='total', line=3, column=17) Token(type='OP', value='+', line=3, column=23) Token(type='ID', value='price', line=3, column=25) Token(type='OP', value='*', line=3, column=31) Token(type='ID', value='quantity', line=3, column=33) Token(type='END', value=';', line=3, column=41) Token(type='ID', value='tax', line=4, column=8) Token(type='ASSIGN', value=':=', line=4, column=12) Token(type='ID', value='price', line=4, column=15) Token(type='OP', value='*', line=4, column=21) Token(type='NUMBER', value=0.05, line=4, column=23) Token(type='END', value=';', line=4, column=27) Token(type='ENDIF', value='ENDIF', line=5, column=4) Token(type='END', value=';', line=5, column=9) </pre></div> </div> <div role="list" class="citation-list"> <div class="citation" id="frie09" role="doc-biblioentry"> [<a role="doc-backlink" href="#id1">Frie09</a>] Friedl, Jeffrey. Mastering Regular Expressions. 3rd ed., O’Reilly Media, 2009. The third edition of the book no longer covers Python at all, but the first edition covered writing good regular expression patterns in great detail. </div> </div> </section> </section> </section> <div class="clearer"></div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="Main"> <div class="sphinxsidebarwrapper"> <div> <h3><a href="../contents.html">Table of Contents</a></h3> <ul> <li><a class="reference internal" href="#"><code class="xref py py-mod docutils literal notranslate">re</code> — Regular expression operations</a><ul> <li><a class="reference internal" href="#regular-expression-syntax">Regular Expression Syntax</a></li> <li><a class="reference internal" href="#module-contents">Module Contents</a><ul> <li><a class="reference internal" href="#flags">Flags</a></li> <li><a class="reference internal" href="#functions">Functions</a></li> <li><a class="reference internal" href="#exceptions">Exceptions</a></li> </ul> </li> <li><a class="reference internal" href="#regular-expression-objects">Regular Expression Objects</a></li> <li><a class="reference internal" href="#match-objects">Match Objects</a></li> <li><a class="reference internal" href="#regular-expression-examples">Regular Expression Examples</a><ul> <li><a class="reference internal" href="#checking-for-a-pair">Checking for a Pair</a></li> <li><a class="reference internal" href="#simulating-scanf">Simulating scanf()</a></li> <li><a class="reference internal" href="#search-vs-match">search() vs. match()</a></li> <li><a class="reference internal" href="#making-a-phonebook">Making a Phonebook</a></li> <li><a class="reference internal" href="#text-munging">Text Munging</a></li> <li><a class="reference internal" href="#finding-all-adverbs">Finding all Adverbs</a></li> <li><a class="reference internal" href="#finding-all-adverbs-and-their-positions">Finding all Adverbs and their Positions</a></li> <li><a class="reference internal" href="#raw-string-notation">Raw String Notation</a></li> <li><a class="reference internal" href="#writing-a-tokenizer">Writing a Tokenizer</a></li> </ul> </li> </ul> </li> </ul> </div> <div> <h4>Previous topic</h4> <a href="string.html" title="previous chapter"><code class="xref py py-mod docutils literal notranslate">string</code> — Common string operations</a> </div> <div> <h4>Next topic</h4> <a href="difflib.html" title="next chapter"><code class="xref py py-mod docutils literal notranslate">difflib</code> — Helpers for computing deltas</a> </div> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li> <a href="https://github.com/python/cpython/blob/main/Doc/library/re.rst" rel="nofollow">Show Source </a> </li> </ul> </div> </div> <div id="sidebarbutton" title="Collapse sidebar"> « </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="Related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="difflib.html" title="difflib — Helpers for computing deltas" >next</a> |</li> <li class="right" > <a href="string.html" title="string — Common string operations" >previous</a> |</li> <li><img src="../_static/py.svg" alt="Python logo" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li class="switchers"> <div class="language_switcher_placeholder"></div> <div class="version_switcher_placeholder"></div> </li> <li> </li> <li id="cpython-language-and-version"> <a href="../index.html">3.13.2 Documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="text.html" >Text Processing Services</a> »</li> <li class="nav-item nav-item-this"><a href=""><code class="xref py py-mod docutils literal notranslate">re</code> — Regular expression operations</a></li> <li class="right"> <div class="inline-search" role="search"> <form class="inline-search" action="../search.html" method="get"> <input placeholder="Quick search" aria-label="Quick search" type="search" name="q" id="search-box" /> <input type="submit" value="Go" /> </form> </div> | </li> <li class="right"> <label class="theme-selector-label"> Theme <select class="theme-selector" oninput="activateTheme(this.value)"> <option value="auto" selected>Auto</option> <option value="light">Light</option> <option value="dark">Dark</option> </select> </label> |</li> </ul> </div> <div class="footer"> © <a href="../copyright.html"> Copyright </a> 2001-2025, Python Software Foundation. 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