{"id":3400,"date":"2021-12-11T02:36:22","date_gmt":"2021-12-11T02:36:22","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=3400"},"modified":"2021-12-11T02:37:16","modified_gmt":"2021-12-11T02:37:16","slug":"python-regex-non-capturing-group","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-regex\/python-regex-non-capturing-group\/","title":{"rendered":"Python Regex Non-capturing Group"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you&#8217;ll learn about the Python regex non-capturing group to create a group but don&#8217;t want to store it in the groups of the match.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='introduction-to-the-python-regex-non-capturing-group'>Introduction to the Python regex non-capturing group <a href=\"#introduction-to-the-python-regex-non-capturing-group\" class=\"anchor\" id=\"introduction-to-the-python-regex-non-capturing-group\" title=\"Anchor for Introduction to the Python regex non-capturing group\">#<\/a><\/h2>\n\n\n\n<p>Regular expressions have two types of groups:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>Capturing groups<\/li><li>Non-capturing groups<\/li><\/ul>\n\n\n\n<p>So far, you learned how to use a <a href=\"https:\/\/www.pythontutorial.net\/python-regex\/python-regex-capturing-group\/\">capturing group<\/a> to extract information from a bigger match or rematch the previous matched group using a <a href=\"https:\/\/www.pythontutorial.net\/python-regex\/python-regex-backreferences\/\">backreference<\/a>.<\/p>\n\n\n\n<p>To do that, you create a capturing group, you place a pattern (or a rule) inside the parentheses, for example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">(X)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>This syntax captures whatever match <code>X<\/code> inside the match so that you can access it via the <code>group()<\/code> method of the <code>Match<\/code> object.<\/p>\n\n\n\n<p>Sometimes, you may want to create a group but don&#8217;t want to capture it in the groups of the match. To do that, you can use a non-capturing group with the following syntax:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">(?:X)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<h2 class=\"wp-block-heading\" id='python-regex-no-capturing-group-example'>Python Regex no-capturing group example <a href=\"#python-regex-no-capturing-group-example\" class=\"anchor\" id=\"python-regex-no-capturing-group-example\" title=\"Anchor for Python Regex no-capturing group example\">#<\/a><\/h2>\n\n\n\n<p>The following example illustrates how to use the capturing groups to capture the major and minor versions of Python in the string <code>\"Python 3.10\"<\/code><\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> re\n\ns = <span class=\"hljs-string\">'Python 3.10'<\/span>\npattern = <span class=\"hljs-string\">'(\\d+)\\.(\\d+)'<\/span>\n\nmatch = re.search(pattern, s)\n\n<span class=\"hljs-comment\"># show the whole match<\/span>\nprint(match.group())\n\n<span class=\"hljs-comment\"># show the groups<\/span>\n<span class=\"hljs-keyword\">for<\/span> group <span class=\"hljs-keyword\">in<\/span> match.groups():\n    print(group)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-number\">3.10<\/span>\n<span class=\"hljs-number\">3<\/span>\n<span class=\"hljs-number\">10<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>The following pattern matches one or more digits followed by the literal string (.) and one or more digits:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-5\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">(\\d+)\\.(\\d+)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-5\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>It has two capturing groups. They capture the digits before and after the literal (.):<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-6\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-number\">3<\/span>\n<span class=\"hljs-number\">10<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-6\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Suppose you don&#8217;t want to capture the digits before the literal character (.), you can use a non-capturing group like this:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-7\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> re\n\ns = <span class=\"hljs-string\">'Python 3.10'<\/span>\npattern = <span class=\"hljs-string\">'(?:\\d+)\\.(\\d+)'<\/span>\n\nmatch = re.search(pattern, s)\n\n<span class=\"hljs-comment\"># show the whole match<\/span>\nprint(match.group())\n\n<span class=\"hljs-comment\"># show the groups<\/span>\n<span class=\"hljs-keyword\">for<\/span> group <span class=\"hljs-keyword\">in<\/span> match.groups():\n    print(group)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-7\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-8\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-number\">3.10<\/span>\n<span class=\"hljs-number\">10<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-8\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example, we use the non-capturing group for the first group:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-9\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\">(?:\\d+)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-9\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>To capture the minor version only, you can ignore the non-capturing group in the first place like this:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-10\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-keyword\">import<\/span> re\n\ns = <span class=\"hljs-string\">'Python 3.10'<\/span>\npattern = <span class=\"hljs-string\">'\\d+\\.(\\d+)'<\/span>\nmatch = re.search(pattern, s)\n\n<span class=\"hljs-comment\"># show the whole match<\/span>\nprint(match.group())\n\n<span class=\"hljs-comment\"># show the groups<\/span>\n<span class=\"hljs-keyword\">for<\/span> group <span class=\"hljs-keyword\">in<\/span> match.groups():\n    print(group)<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-10\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Output:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-11\" data-shcb-language-name=\"Python\" data-shcb-language-slug=\"python\"><span><code class=\"hljs language-python\"><span class=\"hljs-number\">3.10<\/span>\n<span class=\"hljs-number\">10<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-11\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">Python<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">python<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>So why do you use the non-capturing group anyway? the reason for using the non-capturing group is to save memory, as the regex engine doesn&#8217;t need to store the groups in the buffer.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id='summary'>Summary <a href=\"#summary\" class=\"anchor\" id=\"summary\" title=\"Anchor for Summary\">#<\/a><\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li>Use the regex non-capturing group to create a group but don&#8217;t save it in the groups of the match.<\/li><\/ul>\n<div class=\"helpful-block-content\" data-title=\"\">\n\t<header>\n\t\t<div class=\"wth-question\">Was this tutorial helpful ?<\/div>\n\t\t<div class=\"wth-thumbs\">\n\t\t\t<button\n\t\t\t\tdata-post=\"3400\"\n\t\t\t\tdata-post-url=\"https:\/\/www.pythontutorial.net\/python-regex\/python-regex-non-capturing-group\/\"\n\t\t\t\tdata-post-title=\"Python Regex Non-capturing Group\"\n\t\t\t\tdata-response=\"1\"\n\t\t\t\tclass=\"wth-btn-rounded wth-yes-btn\"\n\t\t\t>\n\t\t\t\t<svg\n\t\t\t\t\txmlns=\"http:\/\/www.w3.org\/2000\/svg\"\n\t\t\t\t\tviewBox=\"0 0 24 24\"\n\t\t\t\t\tfill=\"none\"\n\t\t\t\t\tstroke=\"currentColor\"\n\t\t\t\t\tstroke-width=\"2\"\n\t\t\t\t\tstroke-linecap=\"round\"\n\t\t\t\t\tstroke-linejoin=\"round\"\n\t\t\t\t\tclass=\"feather feather-thumbs-up block w-full h-full\"\n\t\t\t\t>\n\t\t\t\t\t<path\n\t\t\t\t\t\td=\"M14 9V5a3 3 0 0 0-3-3l-4 9v11h11.28a2 2 0 0 0 2-1.7l1.38-9a2 2 0 0 0-2-2.3zM7 22H4a2 2 0 0 1-2-2v-7a2 2 0 0 1 2-2h3\"\n\t\t\t\t\t><\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t<span class=\"sr-only\"> Yes <\/span>\n\t\t\t<\/button>\n\n\t\t\t<button\n\t\t\t\tdata-response=\"0\"\n\t\t\t\tdata-post=\"3400\"\n\t\t\t\tdata-post-url=\"https:\/\/www.pythontutorial.net\/python-regex\/python-regex-non-capturing-group\/\"\n\t\t\t\tdata-post-title=\"Python Regex Non-capturing Group\"\n\t\t\t\tclass=\"wth-btn-rounded wth-no-btn\"\n\t\t\t>\n\t\t\t\t<svg\n\t\t\t\t\txmlns=\"http:\/\/www.w3.org\/2000\/svg\"\n\t\t\t\t\tviewBox=\"0 0 24 24\"\n\t\t\t\t\tfill=\"none\"\n\t\t\t\t\tstroke=\"currentColor\"\n\t\t\t\t\tstroke-width=\"2\"\n\t\t\t\t\tstroke-linecap=\"round\"\n\t\t\t\t\tstroke-linejoin=\"round\"\n\t\t\t\t>\n\t\t\t\t\t<path\n\t\t\t\t\t\td=\"M10 15v4a3 3 0 0 0 3 3l4-9V2H5.72a2 2 0 0 0-2 1.7l-1.38 9a2 2 0 0 0 2 2.3zm7-13h2.67A2.31 2.31 0 0 1 22 4v7a2.31 2.31 0 0 1-2.33 2H17\"\n\t\t\t\t\t><\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t<span class=\"sr-only\"> No <\/span>\n\t\t\t<\/button>\n\t\t<\/div>\n\t<\/header>\n\n\t<div class=\"wth-form hidden\">\n\t\t<div class=\"wth-form-wrapper\">\n\t\t\t<div class=\"wth-title\"><\/div>\n\t\t\t<textarea class=\"wth-message\"><\/textarea>\n\t\t\t<input type=\"button\" name=\"wth-submit\" class=\"wth-btn wth-btn-submit\" id=\"wth-submit\" \/>\n\t\t\t<input type=\"button\" class=\"wth-btn wth-btn-cancel\" value=\"Cancel\" \/>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>In this tutorial, you&#8217;ll learn about the Python regex non-capturing group to create a group but don&#8217;t want to store it in the groups of the match.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":3122,"menu_order":11,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3400","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/pages\/3400","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/comments?post=3400"}],"version-history":[{"count":0,"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/pages\/3400\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/pages\/3122"}],"wp:attachment":[{"href":"https:\/\/www.pythontutorial.net\/wp-json\/wp\/v2\/media?parent=3400"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}