2.3 R code

There are two types of R code in R Markdown/knitr documents: R code chunks, and inline R code. The syntax for the latter is `r R_CODE`, and it can be embedded inline with other document elements. R code chunks look like plain code blocks, but have {r} after the three backticks and (optionally) chunk options inside {}, e.g.,

```{r chunk-label, echo = FALSE, fig.cap = 'A figure caption.'}
1 + 1
rnorm(10)  # 10 random numbers
plot(dist ~ speed, cars)  # a scatterplot

To learn more about knitr chunk options, see Xie (2015) or the web page http://yihui.org/knitr/options. For books, additional R code can be executed before/after each chapter; see before_chapter_script and after_chapter_script in Section 4.4.


Xie, Yihui. 2015. Dynamic Documents with R and Knitr. 2nd ed. Boca Raton, Florida: Chapman; Hall/CRC. http://yihui.org/knitr/.