[Rd] pipes and setNames
Gabor Grothendieck
ggrothend|eck @end|ng |rom gm@||@com
Mon Apr 18 19:59:46 CEST 2022
This is a suggestion for base. Workarounds using packages are not relevant.
Setting names is something that is done a lot.
On Sun, Apr 17, 2022 at 4:49 PM Avi Gross via R-devel
<r-devel using r-project.org> wrote:
>
> Gabor,
>
> It is always interesting to see suggestions for how to extend R, especially what is suggested to
> be base R. But generally extensions need to be needed not just wanted and the ramifications
> must be studied.
>
> I am curious if you looked at existing pipe-like implementations in various packages to see how or
> if they support such functionality.
>
> There are many things we can wish for but with some care if nonstandard evaluation is allowed.
>
> For example, should we allow multiple instances of the underscore (or dot) character to each be
> replaced by the same input? That can be tricky.
>
> But a trivial solution is to not use the anonymous function but write your own small accessory function.
> I wrote this trivial one:
>
> renamer <- function(x, fun) { names(x) <- fun(names(x)); x }
>
>
> You can then do this:
>
>
> x |> renamer(toupper)
>
>
> Or use tolower or sort or lots of other functions with no arguments.
>
> It is easy to generalize this to functions that allow additional arguments:
>
>
> renamer2 <- function(x, fun, ...) { names(x) <- fun(names(x), ...); x }
>
>
> x |> renamer2(sort, decreasing=TRUE)
>
>
> Clearly this is not a general solution and a suggestion that I might like is to allow a
> compound condition in the pipeline that lets you capture the argument into a named
> variable and then use it as you wish. BUT in a very real sense the anonymous
> function syntax gives you something like that even if a tad ugly to you. However
> things that look wrong to you or may make no sense to others may well
> be avoided.
>
> So your suggestion for an extension to existing functions to allow not repeating the
> name twice makes sense but R supports many attributes you may want to be
> able to manipulate in a pipeline including classes, dimensions, column names,
> row names and much more you can add on your own arbitrarily.
>
> What method might be more generalizable to solve many such problems
> if used along with the new or previous pipes?
>
>
>
>
>
>
> -----Original Message-----
> From: Gabor Grothendieck <ggrothendieck using gmail.com>
> To: r-devel using r-project.org <r-devel using r-project.org>
> Sent: Sun, Apr 17, 2022 8:21 am
> Subject: [Rd] pipes and setNames
>
>
> When trying to transform names in a pipeline one can do the following
>
> where for this example we are making names upper case.
>
>
>
> BOD |> (\(x) setNames(x, toupper(names(x))))()
>
>
>
> but that seems a bit ugly and verbose.
>
>
>
> 1. One possibility is to enhance setNames to allow a function as a
>
> second argument. In that case one could write:
>
>
>
> BOD |> setNames(toupper)
>
>
>
> 2. One can already do the following with the existing `with` but is
>
> quite verbose:
>
> BOD |> list() |> setNames(".") |> with(setNames(., toupper(names(.))))
>
> but could be made simpler with a utility function.
>
>
>
> This utility function is not as good for setNames but would still
>
> result in shorter code than the anonymous function in the example at
>
> the top of this email and is more general so it would also apply in
>
> other situations too. Here R would define a function with. (note dot
>
> at end) which would be defined and used as follows.
>
>
>
> with. <- function(data, expr, ...) {
>
> eval(substitute(expr), list(. = data), enclos = parent.frame())
>
> }
>
>
>
> BOD |> with.(setNames(., toupper(names(.))))
>
>
>
> with. is not as efficient as straight pipes but in many cases such as
>
> this it does not really matter and one just wants to get it done
>
> without the parenthesis laden anonymous function.
>
>
>
> Having both of these two would be nice to make it easier to use R pipes.
>
>
>
> --
>
> Statistics & Software Consulting
>
> GKX Group, GKX Associates Inc.
>
> tel: 1-877-GKX-GROUP
>
> email: ggrothendieck at gmail.com
>
>
>
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