*If* I understand correctly -- and please let me know if I don't -- this seems somewhat more straightforward and less "hacky" :
> desub <- function(x) as.name(all.vars(sys.call(-1))) Yielding in the OP's example: > g <- function(y)desub(y) > g(log) log Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Mon, Dec 12, 2016 at 2:07 PM, Fox, John <[email protected]> wrote: > Dear Frederick, > > I found this a challenging puzzle, and it took me awhile to come up with an > alternative, and I think slightly simpler, solution: > >> desub <- function(y) { > + deparse(eval(substitute(substitute(y)), > + env=parent.frame())) > + } > >> f <- function(x){ > + message(desub(x)) > + } > >> f(log) > log > > Best, > John > > ----------------------------- > John Fox, Professor > McMaster University > Hamilton, Ontario > Canada L8S 4M4 > Web: socserv.mcmaster.ca/jfox > > > > >> -----Original Message----- >> From: R-help [mailto:[email protected]] On Behalf Of >> [email protected] >> Sent: December 11, 2016 8:35 PM >> To: [email protected] >> Subject: Re: [R] how do I define a function which is equivalent to >> `deparse(substitute(x))`? >> >> 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... >> >> 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, [email protected] wrote: >> > >Dear R-Help, >> > > >> > >I asked this question on StackOverflow, >> > > >> > >http://stackoverflow.com/questions/41083293/in-r-how-do-i-define-a-fu >> > >nction-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 >> > > >> > >______________________________________________ >> > >[email protected] 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. >> > >> >> ______________________________________________ >> [email protected] 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. > > ______________________________________________ > [email protected] 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. ______________________________________________ [email protected] 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.
