[R] Understanding the workflow between sweave, R and Latex

[Duncan Murdoch]

On 30/09/2011 8:03 AM, syrvn wrote:
> Let's say I have written the following tiny .Rnw file:
>
> _________________________________________
> \documentclass{article}
>
> \usepackage[utf8]{inputenc}
>
> \usepackage{Sweave}
>
> \usepackage{tikz}
>
> \usepackage{pgf}
>
> \begin{document}
>
> <<>>=
>
> sessionInfo()
>
> @
>
> \end{document}
> _________________________________________
>
> I then can go to R and use sweave to translate the .Rnw file into a .tex
> file
>
> Once this is done the latex interpreter can be called and because I used
>
> \usepackage{Sweave} Latex knows how to handle the sweave specific code tags.
>
> When I first did this procedure I got the commong error that the Sweave.sty
> file could
>
> not be found. I googled and could solve the problem by typing the following
> command
>
> into the Mac OS Terminal:
>
> _________________________________________
> mkdir -p ~/Library/texmf/tex/latex
>
> cd ~/Library/texmf/tex/latex
>
> ln -s /Library/Frameworks/R.framework/Resources/share/texmf Sweave
> _________________________________________
>
> What I don't understand now is how does the latex package
> \usepackage{Sweave} know that it
>
> has to look at ~/Library/texmf/tex/latex to find the symbolic link to the
> Sweave.sty file?
>
> What happens if I change the following line:
>
> ln -s /Library/Frameworks/R.framework/Resources/share/texmf Sweave
>
> to
>
> ln -s /Library/Frameworks/R.framework/Resources/share/texmf Sweave_Link
>
> In the .Rnw file do I have to use then \usepackage{Sweave_Link}?

No.  You need to read up on LaTeX documentation, and particularly on the 
documentation for your particular implementation, to find out how it 
searches for packages, but in general it is looking for the file named 
Sweave.sty, and the directory containing it could be named anything.

As an aside, I don't recommend the workflow you describe:  it's very 
slow and cumbersome.  It's much better to tell your text editor how to 
run both Sweave and Latex in one command.  In the upcoming release of R 
2.14.0, this is a single command:  R CMD Sweave --pdf.  In earlier 
releases, it's only slightly more complicated:  you need to process the 
Rnw to tex, then the tex to pdf using pdflatex or similar.  (You can do 
more elaborate conversions using my patchDVI package; it's on R-forge, 
here:  https://r-forge.r-project.org/R/?group_id=233).

Duncan Murdoch