[R] inserting R code in a latex document

[Frank E Harrell Jr]

I have been trying to use the listings package in LaTeX to do this but 
have not been fully happy with the result.  Here is what I'm trying:

\lstloadlanguages{R}
\lstset{language=R,basicstyle=\smaller[2],commentstyle=\rmfamily\smaller,
  showstringspaces=false,%
  xleftmargin=4ex,literate={<-}{{$\leftarrow$}}1 {~}{{$\sim$}}1}
\newcommand{\co}[1]{{\lstinline|#1|}} # for in-line S phrases
\newcommand{\Co}[1]{{\lstinline|#1|}}

\begin{lstlisting}
... S code ...
\end{lstlisting}

If anyone has a better setup please let me know.  I'm trying to set 
comments in a smaller font and in roman style, and am changing <- to 
left arrows and ~ to $\sim$.  This also requires the LaTeX relsize package.

Thanks
-- 
Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University