The R sources already contain an operator like that, though it is not
exported. tools:::`%notin%` is defined as
function (x, y)
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,
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
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