The following works because model.frame looks for things in environment(formula) and ancestral environments thereof. It puts the new things in a child environment of the original environment(formula) so it does not alter the original environment.
f2 <- function (formula, data = NULL) { environment(formula) <- new.env(parent = environment(formula)) assign(envir = environment(formula), "gg", sqrt) model.frame(formula, data = data) } Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf > Of Frank Harrell > Sent: Sunday, December 15, 2013 10:09 AM > To: RHELP > Subject: [R] Simple way to define a function to be used in a formula object > inside another > function > > I would like to do this: > > f <- function(formula, data=NULL) { > gg <- sqrt > model.frame(formula, data=data) > } > x <- y <- 1:10 > f(y ~ gg(x)) > Error in eval(expr, envir, enclos) : could not find function "gg" > > Is there a simple way to get access to gg from within the model.frame > invocation inside f? > > Thanks > Frank > > ______________________________________________ > 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. ______________________________________________ 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.