Re: [R] OK, next Q - a sort of factorial on a vector
Eric, On 2023-06-21 04:02, Eric Berger wrote: Hi Philip, In the decades since you learned R there have been some additions to the language. In particular, R now supports lambda functions. Applying this feature to Ivan's beautiful solution cuts down 7 characters (continuing his golfing analogy) unlist(lapply(seq_along(x), \(i) x[i] * x[-(1:i)])) Amazing! - it reminds me of the old days when there were competitions to write the smallest C programs . . Enjoy your return to R! Thanks! I think I was right to look at R first - it is exactly what I need I think - and the model I am thinking of shouldn't need any grunt that would require rewriting any functions in C or Rust or something . . P. On Tue, Jun 20, 2023 at 8:46 PM Philip Rhoades via R-help wrote: Ivan, On 2023-06-21 03:32, Ivan Krylov wrote: В Wed, 21 Jun 2023 03:13:52 +1000 Philip Rhoades via R-help пишет: This: !(1,2,3,4,5) would give this: (2,3,4,5, 6,8,10, 12,15, 20) Do you mean taking a product of every element of the vector with all following vector elements? A relatively straightforward way would be (given your vector stored in `x`): unlist(lapply(seq_along(x), function(i) x[i] * x[-(1:i)])) Perfect! (I'm sure it could be golfed further.) I will look at Sarah's suggestion too. and this: !(1,2,NA,4,5) would give this: (2,4,5, 8,10, 20) The previous solution seems to give your vector interspersed a bunch of NAs, so one way to continue would be to filter it using v[!is.na [1](v)]. Exactly! Thanks people - it would have taken forever to work that out myself (it has been decades since I looked at R). Phil. -- Philip Rhoades PO Box 896 Cowra NSW 2794 Australia E-mail: p...@pricom.com.au __ 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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Links: -- [1] http://is.na -- Philip Rhoades PO Box 896 Cowra NSW 2794 Australia E-mail: p...@pricom.com.au __ 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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] OK, next Q - a sort of factorial on a vector
Hi Philip, In the decades since you learned R there have been some additions to the language. In particular, R now supports lambda functions. Applying this feature to Ivan's beautiful solution cuts down 7 characters (continuing his golfing analogy) unlist(lapply(seq_along(x), \(i) x[i] * x[-(1:i)])) Enjoy your return to R! On Tue, Jun 20, 2023 at 8:46 PM Philip Rhoades via R-help < r-help@r-project.org> wrote: > Ivan, > > > On 2023-06-21 03:32, Ivan Krylov wrote: > > В Wed, 21 Jun 2023 03:13:52 +1000 > > Philip Rhoades via R-help пишет: > > > >> This: > >> > >>!(1,2,3,4,5) > >> > >> would give this: > >> > >>(2,3,4,5, 6,8,10, 12,15, 20) > > > > Do you mean taking a product of every element of the vector with all > > following vector elements? A relatively straightforward way would be > > (given your vector stored in `x`): > > > > unlist(lapply(seq_along(x), function(i) x[i] * x[-(1:i)])) > > > Perfect! > > > > (I'm sure it could be golfed further.) > > > I will look at Sarah's suggestion too. > > > >> and this: > >> > >>!(1,2,NA,4,5) > >> > >> would give this: > >> > >>(2,4,5, 8,10, 20) > > > > The previous solution seems to give your vector interspersed a bunch of > > NAs, so one way to continue would be to filter it using v[!is.na(v)]. > > > Exactly! > > Thanks people - it would have taken forever to work that out myself (it > has been decades since I looked at R). > > Phil. > -- > Philip Rhoades > > PO Box 896 > Cowra NSW 2794 > Australia > E-mail: p...@pricom.com.au > > __ > 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 > http://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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] OK, next Q - a sort of factorial on a vector
Ivan, On 2023-06-21 03:32, Ivan Krylov wrote: В Wed, 21 Jun 2023 03:13:52 +1000 Philip Rhoades via R-help пишет: This: !(1,2,3,4,5) would give this: (2,3,4,5, 6,8,10, 12,15, 20) Do you mean taking a product of every element of the vector with all following vector elements? A relatively straightforward way would be (given your vector stored in `x`): unlist(lapply(seq_along(x), function(i) x[i] * x[-(1:i)])) Perfect! (I'm sure it could be golfed further.) I will look at Sarah's suggestion too. and this: !(1,2,NA,4,5) would give this: (2,4,5, 8,10, 20) The previous solution seems to give your vector interspersed a bunch of NAs, so one way to continue would be to filter it using v[!is.na(v)]. Exactly! Thanks people - it would have taken forever to work that out myself (it has been decades since I looked at R). Phil. -- Philip Rhoades PO Box 896 Cowra NSW 2794 Australia E-mail: p...@pricom.com.au __ 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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] OK, next Q - a sort of factorial on a vector
vf <- function(x){
o <- outer(x, x)
as.vector(na.omit(o[lower.tri(o)]))
}
vf(1:5)
vf(c(1,2,NA,4,5))
Best,
Uwe Ligges
On 20.06.2023 19:13, Philip Rhoades via R-help wrote:
People,
What I mean is, is there an elegant way to do this:
This:
!(1,2,3,4,5)
would give this:
(2,3,4,5, 6,8,10, 12,15, 20)
and this:
!(1,2,NA,4,5)
would give this:
(2,4,5, 8,10, 20)
?
Thanks!
Phil.
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] OK, next Q - a sort of factorial on a vector
Well, I think this is reasonable elegant, but ymmv. Turning it into a
function and removing NA values is left for you.
> x <- 1:5
> unlist(sapply(seq(1, length(x) - 1), function(i){x[i] * x[seq(i + 1,
> length(x))]}))
[1] 2 3 4 5 6 8 10 12 15 20
>
> x <- c(1, 2, NA, 4, 5)
> unlist(sapply(seq(1, length(x) - 1), function(i){x[i] * x[seq(i + 1,
> length(x))]}))
[1] 2 NA 4 5 NA 8 10 NA NA 20
Sarah
On Tue, Jun 20, 2023 at 1:15 PM Philip Rhoades via R-help
wrote:
>
> People,
>
> What I mean is, is there an elegant way to do this:
>
> This:
>
>!(1,2,3,4,5)
>
> would give this:
>
>(2,3,4,5, 6,8,10, 12,15, 20)
>
> and this:
>
>!(1,2,NA,4,5)
>
> would give this:
>
>(2,4,5, 8,10, 20)
>
> ?
>
> Thanks!
>
> Phil.
> --
> Philip Rhoades
>
> PO Box 896
> Cowra NSW 2794
> Australia
> E-mail: p...@pricom.com.au
>
> __
> 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 http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
--
Sarah Goslee (she/her)
http://www.numberwright.com
__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] OK, next Q - a sort of factorial on a vector
В Wed, 21 Jun 2023 03:13:52 +1000 Philip Rhoades via R-help пишет: > This: > >!(1,2,3,4,5) > > would give this: > >(2,3,4,5, 6,8,10, 12,15, 20) Do you mean taking a product of every element of the vector with all following vector elements? A relatively straightforward way would be (given your vector stored in `x`): unlist(lapply(seq_along(x), function(i) x[i] * x[-(1:i)])) (I'm sure it could be golfed further.) > and this: > >!(1,2,NA,4,5) > > would give this: > >(2,4,5, 8,10, 20) The previous solution seems to give your vector interspersed a bunch of NAs, so one way to continue would be to filter it using v[!is.na(v)]. -- Best regards, Ivan __ 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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
[R] OK, next Q - a sort of factorial on a vector
People, What I mean is, is there an elegant way to do this: This: !(1,2,3,4,5) would give this: (2,3,4,5, 6,8,10, 12,15, 20) and this: !(1,2,NA,4,5) would give this: (2,4,5, 8,10, 20) ? Thanks! Phil. -- Philip Rhoades PO Box 896 Cowra NSW 2794 Australia E-mail: p...@pricom.com.au __ 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 http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
