[R] how do I define a function which is equivalent to `deparse(substitute(x))`?
frederik at ofb.net
frederik at ofb.net
Mon Dec 12 06:55:48 CET 2016
Thank you, that made me laugh :)
On Sun, Dec 11, 2016 at 08:53:42PM -0800, David Winsemius wrote:
>
> > On Dec 11, 2016, at 5:35 PM, frederik at ofb.net wrote:
> >
> > Dear R-Help,
> >
> > I was going to ask Jeff to read the entire works of William
> > Shakespeare to learn why his reply was not helpful to me...
>
> From a typical US 10th grade English assignment:
>
> Cassius:
> "The fault, dear Brutus, is not in our stars,
> But in ourselves, that we are underlings."
>
> --
> David.
> >
> > Then I realized that the answer, as always, lies within...
> >
> > desub <- function(y) {
> > e1=substitute(y, environment())
> > e2=do.call(substitute,list(e1), env=parent.frame())
> > deparse(e2)
> > }
> >
> > Sorry to trouble the list; other solutions still welcome.
> >
> > Cheers,
> >
> > Frederick
> >
> > On Sun, Dec 11, 2016 at 12:46:23AM -0800, Jeff Newmiller wrote:
> >> No. Read Hadley Wickham's "Advanced R" to learn why not.
> >> --
> >> Sent from my phone. Please excuse my brevity.
> >>
> >> On December 10, 2016 10:24:49 PM PST, frederik at ofb.net wrote:
> >>> Dear R-Help,
> >>>
> >>> I asked this question on StackOverflow,
> >>>
> >>> http://stackoverflow.com/questions/41083293/in-r-how-do-i-define-a-function-which-is-equivalent-to-deparsesubstitutex
> >>>
> >>> but thought perhaps R-help would be more appropriate.
> >>>
> >>> I want to write a function in R which grabs the name of a variable
> >>> from the context of its caller's caller. I think the problem I have is
> >>> best understood by asking how to compose `deparse` and `substitute`.
> >>> You can see that a naive composition does not work:
> >>>
> >>> # a compose operator
> >>>> `%c%` = function(x,y)function(...)x(y(...))
> >>>
> >>> # a naive attempt to combine deparse and substitute
> >>>> desub = deparse %c% substitute
> >>>> f=function(foo) { message(desub(foo)) }
> >>>> f(log)
> >>> foo
> >>>
> >>> # this is how it is supposed to work
> >>>> g=function(foo) { message(deparse(substitute(foo))) }
> >>>> g(log)
> >>> log
> >>>
> >>> Is there a way I can define a function `desub` so that `desub(x)` has
> >>> the same value as `deparse(substitute(x))` in every context?
> >>>
> >>> Thank you,
> >>>
> >>> Frederick Eaton
> >>>
> >>> ______________________________________________
> >>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >>> 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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 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.
>
> David Winsemius
> Alameda, CA, USA
>
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