Avi I fear this was all a huge social experiment.
Testing if a post titled "sexy way" would increase engagement... On Sat, 28 Sep 2024, 07:21 , <avi.e.gr...@gmail.com> wrote: > I see a book coming: > "666 ways to do the same thing in R ranked by sexiness." > > Kidding aside, if you look under the covers of some of the functions we > are using, we may find we are taking steps back as some of them use others > and perhaps more functionality than we need. > > But for a new reader , looking at many approaches may open up other ways > and ideas and see the problem space as quite vast. > > -----Original Message----- > From: R-help <r-help-boun...@r-project.org> On Behalf Of Lennart Kasserra > Sent: Saturday, September 28, 2024 1:59 AM > To: Rolf Turner <rolftur...@posteo.net>; r-help@r-project.org; > lennart.kasse...@gmail.com > Subject: Re: [R] Is there a sexy way ...? > > Sorry to append, but I just realised that of course > > ``` > > x |> > pmap(c) |> > reduce(c) |> > unname() > > ``` > > also works and is a general solution in case your list has more than > three elements. Here, we map in parallel over all elements of the list, > always combining the current set of elements into a vector, and then > reduce the resulting list into a vector by combining the elements in > order. This yields a named vector which we can un-name given this was > not desired.n > > All the best, > > Lennart > > Am 28.09.24 um 07:52 schrieb Lennart Kasserra: > > Hi Rolf, > > > > this topic is probably already saturated, but here is a tidyverse > > solution: > > > > ``` > > > > library(purrr) > > > > x <- list( > > `1` = c(7, 13, 1, 4, 10), > > `2` = c(2, 5, 14, 8, 11), > > `3` = c(6, 9, 15, 12, 3) > > ) > > > > x |> > > pmap(~ c(..1, ..2, ..3)) |> > > reduce(c) > > > > #> [1] 7 2 6 13 5 9 1 14 15 4 8 12 10 11 3 > > > > ``` > > > > Here, we map over the elements of the list in parallel (hence pmap), > > always combining the elements at the current position into a vector, > > which will result in a list like this: > > > > ``` > > > > [[1]] > > [1] 7 2 6 > > > > [[2]] > > [1] 13 5 9 > > > > ... > > > > ``` > > > > And then we reduce this resulting list into a vector by successively > > combining its elements with `c()`. I think the formula syntax is a bit > > idiosyncratic, you could also do this with an anonymous function like > > pmap(\(`1`, `2`, `3`) c(`1`, `2`, `3`)), or if the list was unnamed as > > pmap(\(x, y, z) c(x, y, z)). > > > > I personally find the tidyverse-esque code to be very explicit & > > readable, but given base R can do this very concisely one might argue > > that it is superfluous to bring in an extra library for this. I think > > Bert's solution ( > > `c(do.call(rbind, x))`) is great if `f` has no substantive meaning, > > and Deepayan's solution (`unsplit(x, f)`) is perfect in case it does - > > does not get much sexier than that, I am afraid. > > > > Best, > > > > Lennart > > > > > > Am 27.09.24 um 05:55 schrieb Rolf Turner: > >> I have (toy example): > >> > >> x <- list(`1` = c(7, 13, 1, 4, 10), > >> `2` = c(2, 5, 14, 8, 11), > >> `3` = c(6, 9, 15, 12, 3)) > >> and > >> > >> f <- factor(rep(1:3,5)) > >> > >> I want to create a vector v of length 15 such that the entries of v, > >> corresponding to level l of f are the entries of x[[l]]. I.e. I want > >> v to equal > >> > >> c(7, 2, 6, 13, 5, 9, 1, 14, 15, 4, 8, 12, 10, 11, 3) > >> > >> I can create v "easily enough", using say, a for-loop. It seems to me, > >> though, that there should be sexier (single command) way of achieving > >> the desired result. However I cannot devise one. > >> > >> Can anyone point me in the right direction? Thanks. > >> > >> cheers, > >> > >> Rolf Turner > >> > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
