e <- new.env() e$x <- 2 f <- function(a, e) { e$x <- e$x + a; e$x } f(3, e) e$x # 5
Another way to accomplish this is to use the proto package which puts the whole thing into an object oriented framework. See http://r-proto.googlecode.com library(proto) p <- proto(x = 2, f = function(this, a) { this$x <- this$x + a; this$x }) p$f(3) # 5 On Wed, Dec 9, 2009 at 4:54 PM, David Reiss <dre...@systemsbiology.org> wrote: > Hi all, > > I have a somewhat confusing question that I was wondering if someone > could help with. I have a pre-defined environment with some variables, > and I would like to define a function, such that when it is called, it > actually manipulates the variables in that environment, leaving them > to be examined later. I see from the R language definition that > > "When a function is called, a new environment (called the evaluation > environment) is created, whose enclosure (see Environment objects) is > the environment from the function closure. This new environment is > initially populated with the unevaluated arguments to the function; as > evaluation proceeds, local variables are created within it." > > So basically, I think I am asking if it is possible to pre-create my > own "evaluation environment" and have it retain the state that it was > in at the end of the function call? > > Example: > > e <- new.env() > e$x <- 3 > f <- function(xx) x <- x + xx > > can I then call f(2) and have it leave e$x at 5 after the function > returns? I know that > > environment(f) <- e > > goes part of the way, but I would like to let the function also write > to the environment. > > Thanks for any advice. > > --David > > ______________________________________________ > 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.