Suggest you look at dplyr::mutate as this functionality is widely used there and has shown itself to be useful.
On Tue, Aug 27, 2024 at 9:16 AM Sebastian Meyer <seb.me...@fau.de> wrote: > > Am 27.08.24 um 11:55 schrieb peter dalgaard: > > Yes. A quirk, rather than a bug I'd say. One issue is that the internal > > logic of transform() relies on > > > > e <- eval(substitute(list(...)), `_data`, parent.frame()) > > tags <- names(e) > > > > so untagged entries in ... will not be included. > > ... unless at least one is tagged: > > R> transform(BOD, 0:5, 1:6) > Time demand > 1 1 8.3 > 2 2 10.3 > 3 3 19.0 > 4 4 16.0 > 5 5 15.6 > 6 7 19.8 > > R> transform(BOD, 0:5, 1:6, foo = 1) > Time demand 0:5 1:6 foo > 1 1 8.3 0 1 1 > 2 2 10.3 1 2 1 > 3 3 19.0 2 3 1 > 4 4 16.0 3 4 1 > 5 5 15.6 4 5 1 > 6 7 19.8 5 6 1 > > But as transform.data.frame is only documented for tagged vector > expressions, all examples provided in this thread were formal misuses. > (It might make sense to warn about untagged entries.) > > Personally, I'd be quite confused about what to expect from syntax like > > transform(BOD, data.frame(y = 1:6)) > > as really no transformation is specified. Looks like cbind() or > data.frame() was meant. > > Sebastian > > > > The other part is a direct consequence of a quirk in data.frame: > > > >> data.frame(head(airquality), y=data.frame(x=rnorm(6))) > > Ozone Solar.R Wind Temp Month Day x > > 1 41 190 7.4 67 5 1 0.3075402 > > 2 36 118 8.0 72 5 2 0.7765265 > > 3 12 149 12.6 74 5 3 0.3909341 > > 4 18 313 11.5 62 5 4 0.4733170 > > 5 NA NA 14.3 56 5 5 -0.6947709 > > 6 28 NA 14.9 66 5 6 0.1126040 > > > > whereas (the wisdom of this escapes me) > > > >> data.frame(head(airquality), y=data.frame(x=rnorm(6),z=rnorm(6))) > > Ozone Solar.R Wind Temp Month Day y.x y.z > > 1 41 190 7.4 67 5 1 -0.9250228 0.46483406 > > 2 36 118 8.0 72 5 2 -0.5035793 0.28822668 > > ... > > > > On the whole, I think that transform was never designed (nor documented) to > > take data frame arguments, so caveat emptor. > > > > - Peter > > > > > >> On 24 Aug 2024, at 16:41 , Gabor Grothendieck <ggrothendi...@gmail.com> > >> wrote: > >> > >> One oddity in transform that I recently noticed. It seems that to include > >> a one-column data frame in the arguments one must name it even though the > >> name is ignored. If the data frame has more than one column then it must > >> also be named but in that case it is not ignored and the names are made up > >> of > >> a combination of that name and the data frame's names. I would have > >> thought > >> that if we did not want a combination of names we would just not name the > >> argument. > >> > >> # ignores second argument returning BOD unchanged > >> transform(BOD, data.frame(y = 1:6)) |> names() > >> ## [1] "Time" "demand" > >> > >> # ignores second argument returning BOD unchanged > >> transform(BOD, data.frame(y = 1:6, z = 6:1)) |> names() > >> ## [1] "Time" "demand" > >> > >> # with one column in data frame it adds the column and names it y > >> ignoring x > >> transform(BOD, x = data.frame(y = 1:6)) |> names() > >> ## [1] "Time" "demand" "y" > >> > >> # with multiple columns in data frame it uses x.y and x.z as names > >> transform(BOD, data.frame(y = 1:6, z = 6:1)) |> names() > >> ## [1] "Time" "demand" "x.y" "x.z" > >> > >> > >> -- > >> Statistics & Software Consulting > >> GKX Group, GKX Associates Inc. > >> tel: 1-877-GKX-GROUP > >> email: ggrothendieck at gmail.com > >> > >> ______________________________________________ > >> R-devel@r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-devel > > -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
