On Tue, 28 Jun 2005, Luke wrote: > Dear R users, > > I have a data with 1000 variables named "x1", "x2", ..., "x1000", and > I want to construct a formula like this format: > > ~x1+x2+...+x1000+x1:x2+x1:x3+x999:x1000+log(x1)+...+log(x1000) > > That is: the base variables followed by all interaction terms and all > base feature log-transformations. I know I can use several paste > functions to construct it. But is there any other handy way to do it?
Do you really want a formula with over half a million terms in? I think it is likely that R will hit recursion limits in handing such a formula, quite possibly C-level stack overflow. For a more modest example: dd <- data.frame(x1=1, x2=2, x3=3) terms(~ . + .^2, data=dd, simplify=TRUE) will get you all terms and their interactions. Using paste() to get the log terms is the easiest way I know. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
