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<h1>Cull/extract patterns from strings</h1>
<small class="dont-index">Source: <a href='https://github.com/robertschnitman/stringops/blob/master/R/string_cull.R'><code>R/string_cull.R</code></a></small>
<div class="hidden name"><code>string_cull.Rd</code></div>
</div>
<div class="ref-description">
<p>Cull (extract) patterns from strings.</p>
</div>
<pre class="usage"><span class='fu'>string_cull</span><span class='op'>(</span><span class='va'>s</span>, <span class='va'>pattern</span>, get_all <span class='op'>=</span> <span class='cn'>FALSE</span>, collapse <span class='op'>=</span> <span class='st'>','</span>, <span class='va'>...</span><span class='op'>)</span>
<span class='fu'>string_left</span><span class='op'>(</span><span class='va'>s</span>, <span class='va'>n</span><span class='op'>)</span>
<span class='fu'>string_right</span><span class='op'>(</span><span class='va'>s</span>, <span class='va'>n</span><span class='op'>)</span>
<span class='fu'>string_mid</span><span class='op'>(</span><span class='va'>s</span>, <span class='va'>start</span>, <span class='va'>n</span><span class='op'>)</span>
<span class='fu'>string_positions</span><span class='op'>(</span><span class='va'>s</span>, <span class='va'>positions</span>, join <span class='op'>=</span> <span class='cn'>FALSE</span><span class='op'>)</span></pre>
<h2 class="hasAnchor" id="arguments"><a class="anchor" href="#arguments"></a>Arguments</h2>
<table class="ref-arguments">
<colgroup><col class="name" /><col class="desc" /></colgroup>
<tr>
<th>s</th>
<td><p>A string (character) vector.</p></td>
</tr>
<tr>
<th>pattern</th>
<td><p>A regular expression pattern.</p></td>
</tr>
<tr>
<th>get_all</th>
<td><p>Whether to get all matches (TRUE) or not (FALSE).</p></td>
</tr>
<tr>
<th>collapse</th>
<td><p>A separator in the case of multiple matches.</p></td>
</tr>
<tr>
<th>...</th>
<td><p>Inputs get passed to <code><a href='https://rdrr.io/r/base/grep.html'>gregexpr()</a></code>.</p></td>
</tr>
<tr>
<th>start</th>
<td><p>The position in a string at which to start.</p></td>
</tr>
<tr>
<th>n</th>
<td><p>The number of characters.</p></td>
</tr>
<tr>
<th>positions</th>
<td><p>An integer vector of character positions to extract from a string.</p></td>
</tr>
<tr>
<th>join</th>
<td><p>Determines whether to have columns for each position (<code>FALSE</code>) or join the extracted characters together (<code>TRUE</code>).</p></td>
</tr>
</table>
<h2 class="hasAnchor" id="value"><a class="anchor" href="#value"></a>Value</h2>
<p>Character vector.</p>
<h2 class="hasAnchor" id="details"><a class="anchor" href="#details"></a>Details</h2>
<p>The function <code>string_cull()</code> culls (or extracts) a pattern from a string vector--if no pattern is found, <code>NA</code> is returned. Multiple pattern matches are separated by the <code>collapse()</code> input if <code>get_all = TRUE</code>.</p>
<p>The functions <code>string_left()</code>, <code>string_right()</code>, <code>string_mid()</code> act the same as Excel's <code>LEFT()</code>, <code>RIGHT</code>, <code>MID()</code> functions, respectively: they extract a number of characters at a specified starting point (from the beginning for <code>string_left()</code>, from the right for <code>string_right()</code>, and from a specific position for <code>string_mid()</code>).</p>
<p>The function <code>string_positions()</code> pulls the character(s) at specified positions. If <code>join = FALSE</code>, then the extracted characters are split into columns; otherwise, they are concatenated together into a single vector.</p>
<p>The synonym pattern of these functions are <code>s_*()</code> and <code>*()</code> (replace asterisks with cull, left, right, mid, and positions).</p>
<h2 class="hasAnchor" id="see-also"><a class="anchor" href="#see-also"></a>See also</h2>
<div class='dont-index'><p><a href='https://github.com/robertschnitman/stringops'>https://github.com/robertschnitman/stringops</a></p></div>
<h2 class="hasAnchor" id="examples"><a class="anchor" href="#examples"></a>Examples</h2>
<pre class="examples"><div class='input'><span class='fu'>string_cull</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='st'>'^M|a'</span><span class='op'>)</span>
</div><div class='output co'>#> [1] "M" "M" "a" NA "a" "a" NA "M" "M" "M" "M" "M" "M" "M" "a" "a" "a" "a" "a"
#> [20] "a" "a" "a" "a" "a" "a" "a" NA "a" "a" "a" "M" NA </div><div class='input'><span class='fu'>string_cull</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='st'>'^M|a'</span>, get_all <span class='op'>=</span> <span class='cn'>TRUE</span><span class='op'>)</span>
</div><div class='output co'>#> [1] "M,a,a" "M,a,a,a" "a" NA "a" "a,a" NA
#> [8] "M" "M" "M" "M" "M" "M" "M"
#> [15] "a,a" "a" "a" "a" "a" "a,a" "a,a"
#> [22] "a" "a" "a,a" "a" "a" NA "a"
#> [29] "a,a" "a" "M,a,a,a" NA </div><div class='input'><span class='fu'>string_left</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='fl'>3</span><span class='op'>)</span>
</div><div class='output co'>#> [1] "Maz" "Maz" "Dat" "Hor" "Hor" "Val" "Dus" "Mer" "Mer" "Mer" "Mer" "Mer"
#> [13] "Mer" "Mer" "Cad" "Lin" "Chr" "Fia" "Hon" "Toy" "Toy" "Dod" "AMC" "Cam"
#> [25] "Pon" "Fia" "Por" "Lot" "For" "Fer" "Mas" "Vol"</div><div class='input'><span class='fu'>string_right</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='fl'>3</span><span class='op'>)</span>
</div><div class='output co'>#> [1] "RX4" "Wag" "710" "ive" "out" "ant" "360" "40D" "230" "280" "80C" "0SE"
#> [13] "0SL" "SLC" "ood" "tal" "ial" "128" "vic" "lla" "ona" "ger" "lin" "Z28"
#> [25] "ird" "1-9" "4-2" "opa" "a L" "ino" "ora" "42E"</div><div class='input'><span class='fu'>string_mid</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='fl'>2</span>, <span class='fl'>2</span><span class='op'>)</span>
</div><div class='output co'>#> [1] "azd" "azd" "ats" "orn" "orn" "ali" "ust" "erc" "erc" "erc" "erc" "erc"
#> [13] "erc" "erc" "adi" "inc" "hry" "iat" "ond" "oyo" "oyo" "odg" "MC " "ama"
#> [25] "ont" "iat" "ors" "otu" "ord" "err" "ase" "olv"</div><div class='input'><span class='fu'>string_positions</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>1</span>, <span class='fl'>3</span>, <span class='fl'>5</span><span class='op'>)</span><span class='op'>)</span>
</div><div class='output co'>#> 1 3 5
#> [1,] "M" "z" "a"
#> [2,] "M" "z" "a"
#> [3,] "D" "t" "u"
#> [4,] "H" "r" "e"
#> [5,] "H" "r" "e"
#> [6,] "V" "l" "a"
#> [7,] "D" "s" "e"
#> [8,] "M" "r" " "
#> [9,] "M" "r" " "
#> [10,] "M" "r" " "
#> [11,] "M" "r" " "
#> [12,] "M" "r" " "
#> [13,] "M" "r" " "
#> [14,] "M" "r" " "
#> [15,] "C" "d" "l"
#> [16,] "L" "n" "o"
#> [17,] "C" "r" "s"
#> [18,] "F" "a" " "
#> [19,] "H" "n" "a"
#> [20,] "T" "y" "t"
#> [21,] "T" "y" "t"
#> [22,] "D" "d" "e"
#> [23,] "A" "C" "J"
#> [24,] "C" "m" "r"
#> [25,] "P" "n" "i"
#> [26,] "F" "a" " "
#> [27,] "P" "r" "c"
#> [28,] "L" "t" "s"
#> [29,] "F" "r" " "
#> [30,] "F" "r" "a"
#> [31,] "M" "s" "r"
#> [32,] "V" "l" "o"</div><div class='input'><span class='fu'>string_positions</span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/colnames.html'>rownames</a></span><span class='op'>(</span><span class='va'>mtcars</span><span class='op'>)</span>, <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>1</span>, <span class='fl'>3</span>, <span class='fl'>5</span><span class='op'>)</span>, join <span class='op'>=</span> <span class='cn'>TRUE</span><span class='op'>)</span>
</div><div class='output co'>#> [1] "Mza" "Mza" "Dtu" "Hre" "Hre" "Vla" "Dse" "Mr " "Mr " "Mr " "Mr " "Mr "
#> [13] "Mr " "Mr " "Cdl" "Lno" "Crs" "Fa " "Hna" "Tyt" "Tyt" "Dde" "ACJ" "Cmr"
#> [25] "Pni" "Fa " "Prc" "Lts" "Fr " "Fra" "Msr" "Vlo"</div><div class='input'>
</div></pre>
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