[R] Using the pipe, |>, syntax with "names<-"

[Gabor Grothendieck]

This
- is non-destructive (does not change z)
- passes the renamed z onto further pipe legs
- does not use \(x)...

It works by boxing z, operating on the boxed version and then unboxing it.

  z <- data.frame(a = 1:3, b = letters[1:3])
  z |> list(x = _) |> within(names(x)[2] <- "foo") |> _$x
  ##   a foo
  ## 1 1   a
  ## 2 2   b
  ## 3 3   c

On Sat, Jul 20, 2024 at 4:07 PM Bert Gunter <bgunter.4567 using gmail.com> wrote:
>
> This post is likely pretty useless;  it is motivated by a recent post
> from "Val" that was elegantly answered using Tidyverse constructs, but
> I wondered how to do it using base R only. Along the way, I ran into
> the following question to which I think my answer (below) is pretty
> awful. I would be interested in more elegant base R approaches. So...
>
> z <- data.frame(a = 1:3, b = letters[1:3])
> > z
>   a h
> 1 1 a
> 2 2 b
> 3 3 c
>
> Suppose I want to change the name of the second column of z from 'b'
> to 'foo' . This is very easy using nested function syntax by:
>
> names(z)[2] <- "foo"
> > z
>   a foo
> 1 1   a
> 2 2   b
> 3 3   c
>
> Now suppose I wanted to do this using |> syntax, along the lines of:
>
> z |> names()[2] <- "foo"  ## throws an error
>
> Slightly fancier is:
>
> z |> (\(x)names(x)[2] <- "b")()
> ## does nothing, but does not throw an error.
>
> However, the following, which resulted from a more careful read of
> ?names works (after changing the name of the second column back to "b"
> of course):
>
> z |>(\(x) "names<-"(x,value = "[<-"(names(x),2,'foo')))()
> >z
>   a foo
> 1 1   a
> 2 2   b
> 3 3   c
>
> This qualifies to me as "pretty awful." I'm sure there are better ways
> to do this using pipe syntax, so I would appreciate any better
> approaches.
>
> Best,
> Bert
>
> ______________________________________________
> R-help using 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.



-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com