[R] [External Email] Re: how to rename variables by lopping off first 3 characters

[Bert Gunter]

To reply to Heinz's question:
Purely to avoid regex's, which I thought many would view as complex
and mysterious. But I am glad that you posted the regex approach -- I
would agree that it is more elegant, albeit opaque to those unfamiliar
with regex's.

Bert Gunter

On Mon, Mar 14, 2022 at 10:36 AM Christopher W Ryan via R-help
<r-help using r-project.org> wrote:
>
> Thanks! This has gotten me on the right track.  One of my mistakes was that
> I was explicitly using the word select, as in
>
> rename_at(select(starts_with ....
> or
> rename_at(select(vars(starts_with ....
>
> --Chris Ryan
>
> On Mon, Mar 14, 2022 at 1:11 PM Bert Gunter <bgunter.4567 using gmail.com> wrote:
>
> > If you care to entertain this, one of many simple base R ways to do this
> > is:
> >
> > dat <- data.frame(
> > +    i..One = 1:3,
> > +    i..Two = letters[1:3],
> > +    ixx = 5:7)
> > > dat
> >   i..One i..Two ixx
> > 1      1      a   5
> > 2      2      b   6
> > 3      3      c   7
> >
> > > nm <- names(dat)
> > > nm <- ifelse(substring(nm, 1,3) == "i..",
> > +              substring(nm,4),
> > +              nm)
> > > names(dat) <- nm
> > > dat
> >   One Two ixx
> > 1   1   a   5
> > 2   2   b   6
> > 3   3   c   7
> >
> > 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, Mar 14, 2022 at 9:27 AM Christopher W Ryan via R-help
> > <r-help using r-project.org> wrote:
> > >
> > > I have data coming to me from another source, in which some of the
> > variable
> > > names begin with "i.."
> > >
> > > As in "i..actual_meaningful_var_name"
> > >
> > > I would like to remove the first three characters from any variable name
> > if
> > > they are "i.."
> > >
> > > I'm using R on Win 10 and dplyr, so ideally I'm looking for a dplyr
> > > solution. Apparently I'm just not understanding how the various select,
> > > contains, rename_at, rename_with, and so-on dplyr expressions work. I've
> > > tried various arrangements of them, usually resulting in
> > >
> > > Error: `contains()` must be used within a *selecting* function.
> > > i See <https://tidyselect.r-lib.org/reference/faq-selection-context.html
> > >
> > >
> > > A simple select(contains(foo)) I can do fine, to select a subset of
> > > variables. It's combining it with renaming that I am struggling with.
> > >
> > > Grateful for any advice.
> > >
> > > Thanks.
> > >
> > > --Chris Ryan
> > >
> > >         [[alternative HTML version deleted]]
> > >
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> > > and provide commented, minimal, self-contained, reproducible code.
> >
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
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