EVOLUTION-MANAGER
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Extract Data From First Regular Expression Match Into a Data...</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for re_exec {rematch2}"><tr><td>re_exec {rematch2}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2>Extract Data From First Regular Expression Match Into a Data Frame</h2> <h3>Description</h3> <p>Match a regular expression to a string, and return matches, match positions, and capture groups. This function is like its <code><a href="re_match.html">match</a></code> counterpart, except it returns match/capture group start and end positions in addition to the matched values. </p> <h3>Usage</h3> <pre> re_exec(text, pattern, perl = TRUE, ...) ## S3 method for class 'rematch_records' x$name ## S3 method for class 'rematch_allrecords' x$name </pre> <h3>Arguments</h3> <table summary="R argblock"> <tr valign="top"><td><code>text</code></td> <td> <p>Character vector.</p> </td></tr> <tr valign="top"><td><code>pattern</code></td> <td> <p>A regular expression. See <code><a href="../../base/html/regex.html">regex</a></code> for more about regular expressions.</p> </td></tr> <tr valign="top"><td><code>perl</code></td> <td> <p>logical should perl compatible regular expressions be used? Defaults to TRUE, setting to FALSE will disable capture groups.</p> </td></tr> <tr valign="top"><td><code>...</code></td> <td> <p>Additional arguments to pass to <code><a href="../../base/html/gregexpr.html">gregexpr</a></code> (or <code><a href="../../base/html/regexpr.html">regexpr</a></code> if <code>text</code> is of length zero).</p> </td></tr> <tr valign="top"><td><code>x</code></td> <td> <p>Object returned by <code>re_exec</code> or <code>re_exec_all</code>.</p> </td></tr> <tr valign="top"><td><code>name</code></td> <td> <p><code>match</code>, <code>start</code> or <code>end</code>.</p> </td></tr> </table> <h3>Value</h3> <p>A tidy data frame (see Section “Tidy Data”). Match record entries are one length vectors that are set to NA if there is no match. </p> <h3>Tidy Data</h3> <p>The return value is a tidy data frame where each row corresponds to an element of the input character vector <code>text</code>. The values from <code>text</code> appear for reference in the <code>.text</code> character column. All other columns are list columns containing the match data. The <code>.match</code> column contains the match information for full regular expression matches while other columns correspond to capture groups if there are any, and PCRE matches are enabled with <code>perl = TRUE</code> (this is on by default). If capture groups are named the corresponding columns will bear those names. </p> <p>Each match data column list contains match records, one for each element in <code>text</code>. A match record is a named list, with entries <code>match</code>, <code>start</code> and <code>end</code> that are respectively the matching (sub) string, the start, and the end positions (using one based indexing). </p> <h3>Extracting Match Data</h3> <p>To make it easier to extract matching substrings or positions, a special <code>$</code> operator is defined on match columns, both for the <code>.match</code> column and the columns corresponding to the capture groups. See examples below. </p> <h3>See Also</h3> <p><code><a href="../../base/html/regexpr.html">regexpr</a></code>, which this function wraps </p> <p>Other tidy regular expression matching: <code><a href="re_exec_all.html">re_exec_all</a>()</code>, <code><a href="re_match_all.html">re_match_all</a>()</code>, <code><a href="re_match.html">re_match</a>()</code> </p> <h3>Examples</h3> <pre> name_rex <- paste0( "(?<first>[[:upper:]][[:lower:]]+) ", "(?<last>[[:upper:]][[:lower:]]+)" ) notables <- c( " Ben Franklin and Jefferson Davis", "\tMillard Fillmore" ) # Match first occurrence pos <- re_exec(notables, name_rex) pos # Custom $ to extract matches and positions pos$first$match pos$first$start pos$first$end </pre> <hr /><div style="text-align: center;">[Package <em>rematch2</em> version 2.1.2 <a href="00Index.html">Index</a>]</div> </body></html>