On Tue, Apr 21, 2009 at 11:06 PM, Paul Johnson <pauljoh...@gmail.com> wrote: > Can I please have an example of how to use the ifelse package for > LaTeX with LyX? I want to manage a NoWeb/Literate programming > document so that some commands are included in the document only > sometimes. (I'm sending LyX documents to R through Sweave: > http://wiki.lyx.org/LyX/LyxWithRThroughSweave. > > This ERT makes sure that R- Sweave drops the images in a folder "foo" > and prefixes all with "bar". > > \SweaveOpts{prefix.string=foo/bar} > > This is a NoWeb "code chunk" that will create an image in foo called > bar-testfn.eps. > > <<testfn, fig=true, include=false>>= > curve(sin, from = 1, to = 5) > @ > > > Then the image can be used later with some LaTeX: > > \includegraphics{foo/bar-testfn} > > I would like to conditionalize the figure creation, so that only when > I really want new figures will the code chunk be executed. > > In the r-help list I asked about ways to avoid re-doing calculations, > but the answers were focused on ways in which R calculations can be > cached, rather than avoiding asking R for calculations in the first > place. Since I am doing this work within LyX, and LyX has its own way > of handling the temporary LaTeX files, it is not immediately apparent > that the caching strategies proposed from within R are going to help > (the LyX "current working directory" is an unpredictable directory > inside /tmp while the R working directory is inside there, and the R > stuff disappears once LyX exits. > > I'm sorry, this is hard to explain. If you can just give me a > concrete ifthen example in ERT, I think I can make it work. I just > don't understand the ifelse package instructions because they assume a > person is fluent in LaTeX.
Perhaps you should take a look at the Branch feature: section 6.8 of the User's Guide. Clearly this feature should be better publicized.... Bennett
