[Tex/LaTex] Include Sweave input as verbatim

Question

How do I keep Sweave from compiling things in a verbatim environment? For example:

\documentclass{article}
\begin{document}
\begin{verbatim}
<<>>=
1+1
@ 
\end{verbatim}
\end{document}

Results for me in a pdf with:

\begin{Schunk}
\begin{Sinput}
> 1+1
\end{Sinput}
\begin{Soutput}
[1] 2
\end{Soutput}
\end{Schunk}

But I just wanted the input commands.

---

To be more clear, I want the output in this pdf file to be exactly:

<<>>= 
1+1 
@

Answer 1

If you're willing to add a single space before the <<>> and the @, that'll do the trick. (The Sweave driver only interprets as chunks blocks of text beginning with <<>>= at the beginning of a line -- no spaces allowed!)

Your input file will now look like this:

\documentclass{article}
\begin{document}
\begin{verbatim}
 <<>>=
 1+1
 @ 
\end{verbatim}
\end{document}

And your output file will look like this, possibly indented, but without leading spaces:

 <<>>=
 1+1
 @

ADDED LATER

Alternatively, you can use a chunk of R code that, when Sweave'd, uses cat() to output the desired tex code. This solution is probably formally better (in some sense), and also works as desired:

<<results=tex, echo=FALSE>>=
cat("",
"\\begin{verbatim}",
"<<>>=\n",
"1+1\n",
"@\n",
"\\end{verbatim}")
@