I wonder what would be the formal relationship between %in% and %notin%, which will be relevant if these operators are made generic in the future. Is `%notin%` defined as a boolean negation of `%in%`, is it the other way around, or are they entirely independent definitions that just happen to have complementary semantics?
I would be in favor of defining %notin% as a sugar for !x %in% y Best, Taras > On 1 Dec 2025, at 21:23, Kevin Ushey <[email protected]> wrote: > > 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 <[email protected]> > 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 <[email protected]> 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, Ciências e Humanidades >>>>> Universidade de São Paulo >>>>> Av. Arlindo Bettio, 1000, >>>>> Sala Paulo Freire (Sala Coletiva 252), Prédio I1 >>>>> Ermelino Matarazzo, São Paulo, SP, Brasil >>>>> CEP 03828-000 >>>>> Tel.: (11) 3091-8894 >>>>> Em qui., 27 de nov. de 2025 às 14:15, Duncan Murdoch >>>>> <[email protected] <mailto:[email protected]>> 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, Ciências e Humanidades >>>>>> Universidade de São Paulo >>>>>> Av. Arlindo Bettio, 1000, >>>>>> Sala Paulo Freire (Sala Coletiva 252), Prédio I1 >>>>>> Ermelino Matarazzo, São Paulo, SP, Brasil >>>>>> CEP 03828-000 >>>>>> Tel.: (11) 3091-8894 >>>>>> >>>>>> [[alternative HTML version deleted]] >>>>>> >>>>>> ______________________________________________ >>>>>> [email protected] <mailto:[email protected]> mailing list >>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel <https:// >>>>> stat.ethz.ch/mailman/listinfo/r-devel> >>>>> >>>> >>>> ______________________________________________ >>>> [email protected] mailing list >>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>>> >>> >> >> ______________________________________________ >> [email protected] mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
