Reduce space between Sinput and Soutput

Question

I'm using Sweave in the book document class, and I'm getting really huge spacing between Sinput and Soutput evironments.

\documentclass[11pt]{book}
\usepackage{Sweave}
\usepackage{boxedminipage}


\begin{document}


...

\begin{boxedminipage}{1\textwidth}
\begin{Schunk}
\begin{Sinput}
> 3 + 3
\end{Sinput}
\begin{Soutput}
[1] 6
\end{Soutput}
\begin{Sinput}
> 2 * 4
\end{Sinput}
\begin{Soutput}
[1] 8
\end{Soutput}
\begin{Sinput}
> (369 - 1)/6
\end{Sinput}
\begin{Soutput}
[1] 61.33333
\end{Soutput}
\end{Schunk}
\end{boxedminipage}

...
\end{document}

And the end result looks like this:

Any advice for how to reduce that spacing?

Answer 1

Sweave uses fancyvrb to format its code, so the fix requires changing the vertical space in the within that package. Since that is not a user-changeable parameter, we need to patch the \FV@ListVSpace command. I've done this using the etoolbox package, which provides a number of cool tools for patching commands.

\documentclass{article}
\usepackage{Sweave}
\usepackage{boxedminipage}
\usepackage{etoolbox}

\makeatletter
\patchcmd{\FV@ListVSpace}{\@topsepadd\topsep}{}{}
\makeatother

\begin{document}

\begin{boxedminipage}{1\textwidth}
\begin{Schunk}
\begin{Sinput}
> 3 + 3
\end{Sinput}
\begin{Soutput}
[1] 6
\end{Soutput}
\begin{Sinput}
> 2 * 4
\end{Sinput}
\begin{Soutput}
[1] 8
\end{Soutput}
\begin{Sinput}
> (369 - 1)/6
\end{Sinput}
\begin{Soutput}
[1] 61.33333
\end{Soutput}
\end{Schunk}
\end{boxedminipage}

Answer 2

Include the following code into your document after having loaded Sweave:

\newlength{\fancyvrbtopsep}
\newlength{\fancyvrbpartopsep}
\makeatletter
\FV@AddToHook{\FV@ListParameterHook}{\topsep=\fancyvrbtopsep\partopsep=\fancyvrbpartopsep}
\makeatother

Now you'll be able to controll the spacing around the Sinput and Soutput environments by using the following two lengths:

• \fancyvrbtopsep
• \fancyvrbpartopsep

Both act quite similar most of the time, more details can be found in the fancyvrb documentation on page 46.

To kill all extra spacing between the environments, use

\setlength{\fancyvrbtopsep}{0pt}
\setlength{\fancyvrbpartopsep}{0pt}

If you want to reduce the spacing without removing it completely, set \fancyvrbtopsep or \fancyvrbpartopsep to the desired value, e.g. \setlength{\fancyvrbtopsep}{3mm}.

---

Explanation:

Sweave.sty is based on fancyvrb, which uses a list to display its contents and to control margins and spacing. (Actually, it's a bit more complicated, as fancyvrb uses a mixture of rewritten parts of the list code in the LaTeX kernel and the original macro calls.) The appearance of lists can be controlled by \topsep, \partopsep, \itemsep, \parsep, ...

In this special case, only the values \topsep and \partopsep as described above are important. You cannot, however, simply set these values e.g. in the preamble as they are overwritten by the class-specific default values (stored in \@listi, \@listii, ...) when a new list is created.

Instead, you have to hook into the fancyvrb code after these changes have been made, which can be done by adding the necessary code to \FV@ListParameterHook.