On Mon, Jun 20, 2011 at 9:08 AM, albeam <beam.and...@gmail.com> wrote:
> Please allow me to clarify my original question. What I really need to be
> able to do it is to take arbitrary functions and evaluate them for arbitrary
> parameter values. I'm doing the optimization myself, so I need to be able to
> take a user's function and evaluate them at the current parameter values
> during my optimization process. So it would look something like this:
>
> opt.fun <- function(user.formula, param.values)
> {
> #--- I would do some optimization here ---#
>
> fitted.values <- eval.fun(user.formula, param.values) ##<---- this is
> what I need
> }
>
> Where fitted.values is a vector of the same size as the x-values in
> user.formula. nls() does this somehow. I could do this easily myself if I
> have the user pass the formula in reverse polish notation, but I was hoping
> there was a more canonical was to do this in R.
fn in gsubfn, when used to preface a function like this, will convert
certain formula arguments to functions. Here we preface the identity
function so that we just get back the converted argument directly:
> library(subfn)
> fo <- ~ x + 1 # or fo <- x ~ x + 1
> fn$identity(fo)
function (x)
x + 1
See
http://gsubfn.googlecode.com
?fn
vignette("gsubfn")
--
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.
