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

[Gabor Grothendieck]

If you object to names(x)[2]<- ... then use replace:

  z |> list(x = _) |> within(replace(names(x), 2, "foo")) |> _$x

On Sun, Jul 21, 2024 at 11:10 AM Bert Gunter <bgunter.4567 using gmail.com> wrote:
>
> hmmm...
> But note that you still used the nested assignment, names()[2] <-
> "foo", to circumvent R's pipe limitations, which is exactly what
> Iris's solution avoids. So I think I was overawed by your cleverness
> ;-)
>
> Best,
> Bert
>
>
> On Sun, Jul 21, 2024 at 8:01 AM Bert Gunter <bgunter.4567 using gmail.com> wrote:
> >
> > Wow!
> > Yes, this is very clever -- way too clever for me -- and meets my
> > criteria for a solution.
> >
> > I think it's also another piece of evidence of why piping in base R is
> > not suited for complex/nested assignments, as discussed in Deepayan's
> > response.
> >
> > Maybe someone could offer a better Tidydata piping solution just for
> > completeness?
> >
> > Best,
> > Bert
> >
> > On Sun, Jul 21, 2024 at 7:48 AM Gabor Grothendieck
> > <ggrothendieck using gmail.com> wrote:
> > >
> > > 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



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