On Mon, Jul 4, 2011 at 4:11 AM, Joshua Wiley <jwiley.ps...@gmail.com> wrote: > Hi All, > > I have constructed two expressions (e1 & e2). I can see that they are > not identical, but I cannot figure out how they differ. > > ############### > dat <- mtcars > e1 <- expression(with(data = dat, lm(mpg ~ hp))) > e2 <- as.expression(substitute(with(data = dat, lm(f)), list(f = mpg ~ hp))) > > str(e1) > str(e2) > all.equal(e1, e2) > identical(e1, e2) # false > > eval(e1) > eval(e2) > ################ > > The context is trying to use a list of formulae to generate several > models from a multiply imputed dataset. The package I am using (mice) > has methods for with() and that is how I can (easily) get the pooled > results. Passing the formula directly does not work, so I was trying > to generate the entire call and evaluate it as if I had typed it at > the console, but I am missing something (probably rather silly). >
In e1, mpg ~ hp is a call object but in e2 its a formula with an environment: > e1[[1]][[3]][[2]] mpg ~ hp > e2[[1]][[3]][[2]] mpg ~ hp > > class(e1[[1]][[3]][[2]]) [1] "call" > class(e2[[1]][[3]][[2]]) [1] "formula" > > environment(e2[[1]][[3]][[2]]) <environment: R_GlobalEnv> -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ 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.
