Display the knitr code chunk source in document

Question

I'm trying to output the source of a knitr chunk onto a beamer slide.

For example, I would like the following code chunk to be displayed as is in the .Rnw:

<<code-chunk, echo=TRUE, tidy=TRUE>>=
@

I've attempted to recreate this behavior using:

<<out-first-code-chunk, echo=FALSE, comment=NA>>=
cat(paste("<<example-code-chunk, echo=TRUE, tidy=TRUE>>=","@",sep="\n"))
@

This code is legitimate since the cat command in R's console gives:

> cat('<<example-code-chunk, echo=TRUE, tidy=TRUE>>=','@',sep='\n')
<<code-chunk, echo=TRUE, tidy=TRUE>>=
@

However, the resulting latex:

\begin{frame}
\frametitle{Code Chunk}
To incorporate R code into your knitr documents
\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}
\begin{verbatim}
<<example-code-chunk, echo=TRUE, tidy=TRUE>>=
@
\end{verbatim}
\end{kframe}
\end{knitrout}

Throws errors:

<<example-code-chunk, echo=TRUE, tidy=TRUE>>= @ \end {verbatim} \end
\ETC. ! Paragraph ended before \@xverbatim was complete. <to be read
again> \par l.198 \end{frame} I suspect you've forgotten a `}',
causing me to apply this control sequence to too much text. How can we
recover? My plan is to forget the whole thing and hope for the best. !
LaTeX Error: \begin{verbatim} on input line 198 ended by
\end{beamer@framepau ses}. See the LaTeX manual or LaTeX Companion for
explanation. Type H <return> for immediate help. ... l.198 \end{frame}
Your command was ignored. Type I <command> <return> to replace it with
another command, or <return> to continue without it. ! LaTeX Error:
\begin{kframe} on input line 198 ended by \end{beamer@frameslide }.

Why is the latex environment thinking that verbatim was not closed? Is there a more appropriate way to display a code-chunk in its entirety?

Answer 1

This should do it...

1 line in the setup chunk, and 1 extra param in the chunk desired for output...

Console:

`install.packages(devtools)`  
`devtools::install_github("thell/knitliteral")`

For .Rnw:

<<"knitr-setup", include=FALSE, cache=FALSE>>=
knitLiteral::kast_on()
@

<<"my_chunk", eval=FALSE, opts.label="literal-literal">>=
# Something that will not be output in the doc.
@

Output:

<<"my_chunk", eval=FALSE>>=
@

---

For .Rmd:

````{r knitr_setup, include=FALSE, cache=FALSE}
knitLiteral::kast_on()
````

````{r my_chunk, opts.label="literal-literal"}
# Something that will not be output in the doc.
````

Output:

````{r my_chunk}
````

^{_{** The use of 4 backticks keeps syntax highlighting as valid R (where used).}}

From this chunk and what you can see in the source of the example Literal Markdown doc and the rendered doc that there is no need to have a complex chunk.

The sweave example file is also available showing the same examples.