[R] Sweave : allowing errors in R code?

[Duncan Murdoch]

On 11-08-08 9:48 PM, Remko Duursma wrote:
> Dear R-helpers,
>
>
> sorry if this is obvious, but I can't find this in the documentation.
>
> I am using Sweave, and have some code that does not actually work - but I
> want to include it anyway, including the error message that R produces.
>
> But on running Sweave() on my .Rnw file, it simply halts when it gets to the
> code chunk with the bad code.
>
> I can use \verbatim{} instead, but then I don't get R's output automatically
> (nor do I get the nice syntax highlighting from the highlight package that I
> am using).

It is not very easy to display errors in Sweave.  I think there are 
intentions to provide more support, but for now it's not there.

The way I've done it is like this:

\begin{Schunk}
\begin{Sinput}
 > t(Y) + X
\end{Sinput}
\begin{Soutput}
Error in t(Y) + X : non-conformable arrays
\end{Soutput}
\end{Schunk}

This is similar to what Sweave would have produced if it displayed 
errors without stopping, so it might work properly with your syntax 
highlighting.  If not, another alternative is to use a combination of 
chunks with eval=false at first to be displayed, then with try() and 
echo=false to do the actual calculation and display of the error.

Duncan Murdoch