...perhaps ?all.vars as in
> form <- y~x+z > all.vars(form) [1] "y" "x" "z" > all.vars(form)[-1] [1] "x" "z" -- Bert On Wed, Nov 7, 2012 at 2:03 PM, Alexander Shenkin <ashen...@ufl.edu> wrote: > Hello, > > I'm trying to extract the independent variables from a formula. The > closest I've been able to come, aside from rolling my own, is the following: > >> a = y ~ b * x >> attr(terms(formula(a)),"variables") > > The reason I'm doing this is that I'm building a grid of points that I > use to construct a 3-d model prediction surface in rgl. If there are > more than two independent variables, I need to set the other ones to 0 > in the dataframe for the predict() routine. In order to do that, I need > to know what those variables are. > > I suspect there's a better way to go about doing what I'm doing (perhaps > using the model.* family of functions). But, in the meantime, just > extracting the independent variables will move me forward. > > Thanks, > Allie > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
