> On May 5, 2016, at 5:12 PM, Spencer Graves
> <spencer.gra...@effectivedefense.org> wrote:
>
> I want a function to evaluate one argument
> in the environment of a data.frame supplied
> as another argument. "attach" works for
> this, but "with" does not. Is there a way
> to make "with" work? I'd rather not attach
> the data.frame.
>
>
> With the following two functions "eval.w.attach"
> works but "eval.w.with" fails:
>
>
> dat <- data.frame(a=1:2)
> eval.w.attach <- function(x, dat){
> attach(dat)
> X <- x
> detach()
> X
> }
>
> eval.w.with <- function(x, dat){
> with(dat, x)
> }
>
> eval.w.attach(a/2, dat) # returns c(.5, 1)
How about using eval( substitute( ...))?
eval.w.sub <- function(expr, datt){
eval( substitute(expr), env=datt)
}
eval.w.sub(a/2, dat)
#[1] 0.5 1.0
--
David.
>
> eval.w.with(a/2, dat) # Error ... 'a' not found
>
>
> Thanks, Spencer Graves
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA
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