knitr Reference Card

1 Syntax

* denotes local chunk options, e.g., <<label, eval=FALSE>>=; x denotes inline R code, e.g., `r 1+2`.

2 Minimal Examples

\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}

---
title: "An R Markdown document"
---

Hi _Markdown_!

```{r foo, echo=TRUE}
z = 1 + 1
plot(cars)
```

The value of z is `r z`.

3 Chunk Options

opts_chunk controls global chunk options, e.g., knitr::opts_chunk$set(tidy = FALSE), which can be overridden by local chunk options. See all options at https://yihui.org/knitr/options/. Some frequently used options are:

• eval: whether to evaluate the chunk
• echo: whether to echo source code
• results: 'markup', 'asis', 'hold', 'hide'
• tidy: whether to reformat R code
• cache: whether to cache results
• fig.width, fig.height, out.width, out.height: device and output size of figures
• include: whether to include the chunk results in output
• child: path to child documents
• engine: language name (R, python, …)

4 Functions

• knit(): the main function in this package; knit input document and write output
• purl(): extract R code from an input document
• spin(): spin goat’s hair (an R script with roxygen comments) into wool (a literate programming document to be passed to knit())
• stitch(): insert an R script into a template and compile the document
• knit_hooks$set(): set or reset chunk and output hooks

5 Resources

• Homepage: https://yihui.org/knitr/
• Github: https://github.com/yihui/knitr (CRAN)
• Examples: https://github.com/yihui/knitr-examples
• Stack Overflow: https://stackoverflow.com/tags/knitr/