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.
