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<div class="title"><h1>knitr Reference Card</h1></div>
<div class="author"><h2>Yihui Xie</h2></div>
<div class="date"><h3>2024-11-06</h3></div>
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<h2 id="sec:syntax"><span class="section-number main-number">1</span> Syntax</h2>
<table>
<thead>
<tr>
<th>format</th>
<th>start</th>
<th>end</th>
<th>inline</th>
<th>output</th>
</tr>
</thead>
<tbody>
<tr>
<td>Rnw</td>
<td><code><<*>>=</code></td>
<td><code>@</code></td>
<td><code>\Sexpr{x}</code></td>
<td>TeX</td>
</tr>
<tr>
<td>Rmd</td>
<td><code>```{r *}</code></td>
<td><code>```</code></td>
<td><code>`r x`</code></td>
<td>Markdown</td>
</tr>
<tr>
<td>Rhtml</td>
<td><code><!--begin.rcode *</code></td>
<td><code>end.rcode--></code></td>
<td><code><!--rinline x--></code></td>
<td>HTML</td>
</tr>
<tr>
<td>Rrst</td>
<td><code>.. {r *}</code></td>
<td><code>.. ..</code></td>
<td><code>:r:`x`</code></td>
<td>reST</td>
</tr>
<tr>
<td>Rtex</td>
<td><code>% begin.rcode *</code></td>
<td><code>% end.rcode</code></td>
<td><code>\rinline{x}</code></td>
<td>TeX</td>
</tr>
<tr>
<td>Rasciidoc</td>
<td><code>// begin.rcode *</code></td>
<td><code>// end.rcode</code></td>
<td><code>+r x+</code></td>
<td>AsciiDoc</td>
</tr>
<tr>
<td>Rtextile</td>
<td><code>### begin.rcode *</code></td>
<td><code>### end.rcode</code></td>
<td><code>@r x@</code></td>
<td>Textile</td>
</tr>
<tr>
<td>brew</td>
<td></td>
<td></td>
<td><code><% x %></code></td>
<td>text</td>
</tr>
</tbody>
</table>
<p><code>*</code> denotes local chunk options, e.g., <code><<label, eval=FALSE>>=</code>; <code>x</code> denotes
inline R code, e.g., <code>`r 1+2`</code>.</p>
<h2 id="sec:minimal-examples"><span class="section-number main-number">2</span> Minimal Examples</h2>
<div class="col-2">
<h3 id="sec:sweave-rnw"><span class="section-number">2.1</span> Sweave (*.Rnw)</h3>
<pre><code class="language-tex">\documentclass{article}
\begin{document}
Below is a code chunk.
<<foo, echo=TRUE>>=
z = 1 + 1
plot(cars)
@
The value of z is \Sexpr{z}.
\end{document}
</code></pre>
<h3 id="sec:r-markdown-rmd"><span class="section-number">2.2</span> R Markdown (*.Rmd)</h3>
<pre><code class="language-md">---
title: "An R Markdown document"
---
Hi _Markdown_!
```{r foo, echo=TRUE}
z = 1 + 1
plot(cars)
```
The value of z is `r z`.
</code></pre>
</div>
<h2 id="sec:chunk-options"><span class="section-number main-number">3</span> Chunk Options</h2>
<p><code>opts_chunk</code> controls global chunk options, e.g.,
<code>knitr::opts_chunk$set(tidy = FALSE)</code>, which can be overridden by local chunk
options. See all options at <a href="https://yihui.org/knitr/options/">https://yihui.org/knitr/options/</a>. Some frequently
used options are:</p>
<ul>
<li><code>eval</code>: whether to evaluate the chunk</li>
<li><code>echo</code>: whether to echo source code</li>
<li><code>results</code>: <code>'markup'</code>, <code>'asis'</code>, <code>'hold'</code>, <code>'hide'</code></li>
<li><code>tidy</code>: whether to reformat R code</li>
<li><code>cache</code>: whether to cache results</li>
<li><code>fig.width</code>, <code>fig.height</code>, <code>out.width</code>, <code>out.height</code>: device and output size
of figures</li>
<li><code>include</code>: whether to include the chunk results in output</li>
<li><code>child</code>: path to child documents</li>
<li><code>engine</code>: language name (R, python, …)</li>
</ul>
<h2 id="sec:functions"><span class="section-number main-number">4</span> Functions</h2>
<ul>
<li><code>knit()</code>: the main function in this package; knit input document and write
output</li>
<li><code>purl()</code>: extract R code from an input document</li>
<li><code>spin()</code>: spin goat’s hair (an R script with roxygen comments) into wool (a
literate programming document to be passed to <code>knit()</code>)</li>
<li><code>stitch()</code>: insert an R script into a template and compile the document</li>
<li><code>knit_hooks$set()</code>: set or reset chunk and output
<a href="https://yihui.org/knitr/hooks/">hooks</a></li>
</ul>
<h2 id="sec:resources"><span class="section-number main-number">5</span> Resources</h2>
<ul>
<li>Homepage: <a href="https://yihui.org/knitr/">https://yihui.org/knitr/</a></li>
<li>Github: <a href="https://github.com/yihui/knitr">https://github.com/yihui/knitr</a>
(<a href="https://cran.r-project.org/package=knitr">CRAN</a>)</li>
<li>Examples: <a href="https://github.com/yihui/knitr-examples">https://github.com/yihui/knitr-examples</a></li>
<li>Stack Overflow: <a href="https://stackoverflow.com/tags/knitr/">https://stackoverflow.com/tags/knitr/</a></li>
</ul>
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