knitr - Is it possible to call external R script from R markdown (.Rmd) in RStudio?

Question

It's fairly trivial to load external R scripts as per this R Sweave example:

<<external-code, cache=FALSE>>=
read_chunk('foo-bar.R')
@

Can the same be done for R Markdown?

Answer 1

Yes.

Put this at the top of your R Markdown file:

```{r setup, echo=FALSE}
opts_chunk$set(echo = FALSE, cache=FALSE)
read_chunk('../src/your_code.R')
```

Delimit your code with the following hints for knitr (just like @yihui does in the example):

## @knitr part1
plot(c(1,2,3),c(1,2,3))

## @knitr part2
plot(c(1,2,3),c(1,2,3))

In your R Markdown file, you can now have the snippets evaluated in-line:

Title
=====

Foo bar baz...

```{r part1}
```

More foo...

```{r part2}
```