two column beamer/sweave slide with grid graphic - r

Question

I'm trying to make a presentation on ggplot2 graphics using beamer + sweave. Some slides should have two columns; the left one for the code, the right one for the resulting graphic. Here's what I tried,
\documentclass[xcolor=dvipsnames]{beamer}
\usepackage{/Library/Frameworks/R.framework/Resources/share/texmf/tex/latex/Sweave}
\usepackage[english]{babel}
\usepackage{tikz}
\usepackage{amsmath,amssymb}% AMS standards
\usepackage{listings}
\usetheme{Madrid}
\usecolortheme{dove}
\usecolortheme{rose}
\SweaveOpts{pdf=TRUE, echo=FALSE, fig=FALSE, eps=FALSE, tidy=T, width=4, height=4}
\title{Reproducible data analysis with \texttt{ggplot2} \& \texttt{R}}
\subtitle{subtitle}
\author{Baptiste Augui\'e}
\date{\today}
\institute{Here}
\begin{document}
\begin{frame}[fragile]
\frametitle{Some text to show the space taken by the title}
\begin{columns}[t] \column{0.5\textwidth}
Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.
\column{0.5\textwidth}
\begin{figure}[!ht]
\centering
<<fig=TRUE>>=
grid.rect(gp=gpar(fill="slateblue"))
#
\end{figure}
\end{columns}
\end{frame}
\begin{frame}[fragile]
\frametitle{Some text to show the space taken by the title}
\begin{columns}[t]
\column{0.5\textwidth}
<<echo=TRUE,fig=FALSE>>=
library(ggplot2)
p <-
qplot(mpg, wt, data=mtcars, colour=cyl) +
theme_grey(base_family="Helvetica")
#
\column{0.5\textwidth}
\begin{figure}[!ht]
\centering
<<fig=TRUE>>=
print(p)
#
\end{figure}
\end{columns}
\end{frame}
\end{document}
And the two pages of output.
I have two issues with this output:
the echo-ed sweave code ignores the columns environment and spans the two columns
the column margins for either graphic are unecessarily wide
Any ideas?
Thanks.

Answer 1

As for the first question, the easy way is to set keep.source=TRUE in SweaveOpts. For more fancy control, see fancyvrb and FAQ #9 of Sweave manual.
The width of the figure can be set by \setkeys{Gin}{width=1.0\textwidth}
here is a slight modification:
... snip ...
\SweaveOpts{pdf=TRUE, echo=FALSE, fig=FALSE, eps=FALSE, tidy=T, width=4, height=4, keep.source=TRUE}
\title{Reproducible data analysis with \texttt{ggplot2} \& \texttt{R}}
... snip ...
\begin{document}
\setkeys{Gin}{width=1.1\textwidth}
... snip...
<<echo=TRUE,fig=FALSE>>=
library(ggplot2)
p <-
qplot(mpg,
wt,
data=mtcars,
colour=cyl) +
theme_grey(base_family=
"Helvetica")
#