How to display verbatim inline r code with backticks using Rmarkdown?

Question

By doubling the backticks in Markdown, it is easy to render some text in code style including the backticks, such as: `r 2+2`. But how to do that with RMark

Answer 1

Here is a satisfactory finding. First define the function

rinline <- function(code){
  html <- '<code  class="r">``` `r CODE` ```</code>'
  sub("CODE", code, html)
}

in an invisible chunk. Then you can show `r 2+2` by typing:

Some R code inline : `r rinline("2+2")` - nice 

Answer 2

Here is a trick that I use. First, note \x60 is `:

> cat('\x60', '\n')
` 

Then you write

`r '\x60r foo+bar\x60'`

which will give you `r foo+bar` in the markdown output, but that will become r foo+bar in the HTML output, so you need to protect the backticks in markdown, using two (or more) backticks. Then you end up with this hairball:

`` `r '\x60r foo+bar\x60'` ``

Your own solution is good, but I'd just define

rinline <- function(code) {
  sprintf('``` `r %s` ```', code)
}

Also see this post for another trick.

Answer 3

I just learnt about the results='asis' option.
So, yet another way; for fun and learning :-)

```{r, results='asis', echo=FALSE}
cat("`` `r 2+2` ``")
```

Answer 4

To anyone looking at this now, you may want to check out the more recent solution here: embed Rmarkdown without knitr evaluation

Essentially you can do:

Some R code inline : `r knitr::inline_expr("2+2")`

I'm guessing that the functionality describe above has been added to knitr directly but it saves us defining the function ourselves.

Answer 5

The solution of Yihui Xie was not displaying the enclosing quotations in the inserted code when rendering a README.md file for a Github repository. In that case I used html code:

<code>&grave;r foo(x)&grave;</code>

Which displays `r foo(x)` inline.