Another useful data point: a large number of CRAN packages also define
their own %nin% / %notin% operators, e.g.
https://github.com/search?q=org%3Acran+%25nin%25&type=code
https://github.com/search?q=org%3Acran+%25notin%25&type=code
I think the broad usage of the operator, and the consensus over its
implementation, makes it a strong candidate for inclusion in R itself.
I imagine a similar justification was used when %||% was added to base
R as well (which I was very glad to see!)
Best,
Kevin
On Fri, Nov 28, 2025 at 3:12?AM Duncan Murdoch <murdoch.duncan at
gmail.com> wrote:>
> On 2025-11-27 6:09 p.m., Simon Urbanek wrote:
> > Given that the args of tools:::%notin% don?t match %in% I'd say it
was just a local use more than any deep thought about general use.
> >
> > Personally, I really like the idea of %notin% because it is very often
that you start typing foo[foo %in% and then realise you want to invert it and
the preceding negation is then cognitively sort of in the wrong place (reads
like "not foo"). I also like %notin% better than %!in% because I think
a salad of special characters makes things harder to read, but that may be just
subjective.
>
> I agree with both points. I generally use inefficient and unnecessary
> parens, i.e. `foo[!(foo %in% baz)]`.
>
> > And to your 'why bother' question - I do think it?s better to
standardise common operators in core rather than have packages re-define it each
time. And certainly just importing something that trivial from another package
is a bad idea given the dependency implications.
>
> If someone is willing to put up with the fallout from the
"masked"
> messages, then I'd also be in favour. (And I'd choose %notin%
rather
> than %!in% or %nin%, but whoever is willing to do the work should make
> that choice.)
>
> > (On the flip side: if you start using it you need to depend on recent
> R which may not be feasible in some environments, but then if that was
> always the argument we?d never add anything new :P).
>
> Or depend on the backports package.
>
> Duncan Murdoch
> >
> > Cheers,
> > Simon
> >
> >
> >> On 28 Nov 2025, at 08:24, Duncan Murdoch <murdoch.duncan at
gmail.com> wrote:
> >>
> >> On 2025-11-27 11:58 a.m., Marcelo Ventura Freire wrote:
> >>> If it is not a rhetorical question about a closed issue (if it
is, tell me and I will shut up), this inclusion [1] would be useful (since it
was exported and rewritten so many times by so many people and will keep being),
[2] would create an uniformization (since it was and will be written under so
many names before), [3] would not break stuff (since it is not altering the
interface of any already existing function nor it is overwriting any symbol with
a diverse use), [4] would not be neither a complex nor a tiringsome inclusion
(even I myself could do it in a single 1-line pull request, hypothetically
speaking) and [5] would benefit users all around.
> >>> I am not naive to the point of believing that an alteration to
the R core would have few repercussions and surely there must be reasons why it
was not done before.
> >>
> >> I don't know why it was added to tools but not exported, but
here is my guess:
> >>
> >> - A member of R Core agrees with you that this operator is useful.
This appears to have happened in 2016 based on the svn log.
> >> - It already existed in some contributed package, but base
packages can't import anything from non-base packages, so it needed to be
added.
> >> - It wasn't exported, because that would break some packages:
> >> - the ones that export something with that name would now
receive a check message about the conflict.
> >> - if those packages stopped exporting it, then any package
that imported from one of them would have to stop doing that, and import it from
the base package instead.
> >> - It is very easy to write your own, or to import one of the
existing ones, so a lot of work would have been generated for not very much
benefit.
> >>
> >> R Core members try to be careful not to generate work for others
unless there's enough of a net benefit to the community. They are very
busy, and many authors of contributed packages who might be affected by this
change are busy too.
> >>
> >>
> >>> But, in the end, this inclusion would be just a seemingly
unharmful syntax sugar that could be shared, like it was with "\" for
the reserved word "function", but with waaaay less work to implement.
> >>
> >> The difference there is that it added new syntax, so as far as I
know, it didn't affect any existing package. Personally I don't see
that it really offered much of a benefit (keystrokes are cheap), but lots of
people are using it, so I guess some others would disagree.>
> >>> If it is not a dumb proposal, I can just include it in the
wishlist of features in Bugzilla as prescribed in the contributor's page or
I can do that PR myself (if you propose more work to others, the sensible thing
to do is at least to offer yourself to do it, right?). In either case, I create
more work to the dev team, perhaps to different people.
> >>
> >> It's hard for you to do the coordination work with all the
existing packages that use a similar operator, so I don't think that's
really feasible.
> >>
> >>> Thanks for taking your time to answer me.
> >>
> >> No problem. I'm sitting in an airport waiting for a plane, so
any distraction is a net benefit for me!
> >>
> >> Duncan Murdoch>
> >>> Marcelo Ventura Freire
> >>> Escola de Artes, Ci?ncias e Humanidades
> >>> Universidade de S?o Paulo
> >>> Av. Arlindo Bettio, 1000,
> >>> Sala Paulo Freire (Sala Coletiva 252), Pr?dio I1
> >>> Ermelino Matarazzo, S?o Paulo, SP, Brasil
> >>> CEP 03828-000
> >>> Tel.: (11) 3091-8894
> >>> Em qui., 27 de nov. de 2025 ?s 14:15, Duncan Murdoch
<murdoch.duncan at gmail.com <mailto:murdoch.duncan at gmail.com>>
escreveu:
> >>> The R sources already contain an operator like that,
though it is not
> >>> exported. tools:::`%notin%` is defined as
> >>> function (x, y)
> >>> is.na <http://is.na>(match(x, y))
> >>> Several CRAN packages export a similar function, e.g.
omnibus, mefa4,
> >>> data.table, hutils, etc. So I think if it was exported by
R that's a
> >>> better name, but since it is easy to write yourself or
import from some
> >>> other package, why bother?
> >>> Duncan Murdoch
> >>> On 2025-11-27 9:19 a.m., Marcelo Ventura Freire via
R-devel wrote:
> >>> > Hello, dear R core developers
> >>> >
> >>> >
> >>> > I have a feature suggestion and, following the
orientations in
> >>> >
https://contributor.r-project.org/rdevguide/chapters/
> >>> submitting_feature_requests.html
<https://contributor.r-project.org/
> >>> rdevguide/chapters/submitting_feature_requests.html>,
> >>> > I have searched in Bugzilla to the best of my
capabilities for
> >>> suggestions
> >>> > like the one I have in mind but found no results
(however, I can
> >>> be wrong).
> >>> >
> >>> > My idea is including this line
> >>> >
> >>> > `%!in%` <- function(x, table) match(x, table,
nomatch = 0L) == 0L
> >>> >
> >>> > between lines 39 and 40 of the file
"src/library/base/R/match.R".
> >>> >
> >>> > My objective is to create a "not in"
operator that would allow us
> >>> to write
> >>> > code like
> >>> >> value %!in% valuelist
> >>> > instead of
> >>> >> ! value %in% valuelist
> >>> > which is in line with writing
> >>> >> value1 != value2
> >>> > instead of
> >>> >> ! value1 == value2
> >>> >
> >>> > I was not able to devise any reasonable way that
such inclusion
> >>> would break
> >>> > any already existing heritage code unless that
operator would be
> >>> defined
> >>> > otherwisely and it would improve (however
marginally) the
> >>> readability of
> >>> > future code by its intuitive interpretation and by
stitching
> >>> together two
> >>> > operators that currently stand apart each other.
> >>> >
> >>> > So, if this suggestion was not already proposed and
if it is seen as
> >>> > useful, I would like to include it in the wishlist
in Bugzilla.
> >>> >
> >>> > I would appreciate any feedback, be it critic or
support, and I
> >>> hope I have
> >>> > not crossed any communicational rule from the group.
> >>> >
> >>> > Many thanks! ?
> >>> >
> >>> >
> >>> >
> >>> > Marcelo Ventura Freire
> >>> > Escola de Artes, Ci?ncias e Humanidades
> >>> > Universidade de S?o Paulo
> >>> > Av. Arlindo Bettio, 1000,
> >>> > Sala Paulo Freire (Sala Coletiva 252), Pr?dio I1
> >>> > Ermelino Matarazzo, S?o Paulo, SP, Brasil
> >>> > CEP 03828-000
> >>> > Tel.: (11) 3091-8894
> >>> >
> >>> > [[alternative HTML version deleted]]
> >>> >
> >>> > ______________________________________________
> >>> > R-devel at r-project.org <mailto:R-devel at
r-project.org> mailing list
> >>> > https://stat.ethz.ch/mailman/listinfo/r-devel
<https://
> >>> stat.ethz.ch/mailman/listinfo/r-devel>
> >>>
> >>
> >> ______________________________________________
> >> R-devel at r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-devel
> >>
> >
>
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