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. 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. (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). 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
