[R] struggling with apply

[Bert Gunter]

Better, I think (no indexing):

t(apply(somematrix,1,function(x)pmin(x,UB)))


Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Wed, May 27, 2020 at 10:56 AM Rui Barradas <ruipbarradas using sapo.pt> wrote:

> Hello,
>
> Try pmin. And loop by column/UB index with sapply/seq_along.
>
>
> sapply(seq_along(UB), function(i) pmin(UB[i], somematrix[,i]))
> #     [,1] [,2] [,3] [,4]
> #[1,]  1.0  5.5  8.5  7.0
> #[2,]  2.5  3.0  8.0 10.5
> #[3,]  2.5  5.5  5.0 10.5
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> Às 18:46 de 27/05/20, Michael Ashton escreveu:
> > Hi -
> >
> > I have a matrix of n rows and 4 columns.
> >
> > I want to cap the value in each column by a different upper bound. So,
> suppose my matrix is
> >
> > somematrix <- matrix(c(1,4,3,6,3,9,12,8,5,7,11,11),nrow=3,ncol=4)
> >> somematrix
> >       [,1] [,2] [,3] [,4]
> > [1,]    1    6   12    7
> > [2,]    4    3    8   11
> > [3,]    3    9    5   11
> >
> > Now I want to have the maximum value in each column described by
> > UB=c(2.5, 5.5, 8.5, 10.5)
> >
> > So that the right answer will look like:
> >       [,1]      [,2]    [,3]   [,4]
> > [1,]    1      5.5     8.5    7
> > [2,]    2.5    3        8     10.5
> > [3,]    2.5   5.5      5    10.5
> >
> > I've tried a few things, like:
> > newmatrix <- apply(somematrix,c(1,2),function(x) min(UB,x))
> >
> > but I can't figure out to apply the relevant element of the UB list to
> the right element of the matrix. When I run the above, for example, it
> takes min(UB,x) over all UB, so I get:
> >
> > newmatrix
> >       [,1] [,2] [,3] [,4]
> > [1,]  1.0  2.5  2.5  2.5
> > [2,]  2.5  2.5  2.5  2.5
> > [3,]  2.5  2.5  2.5  2.5
> >
> > I'm sure there's a simple and elegant solution but I don't know what it
> is!
> >
> > Thanks in advance,
> >
> > Mike
> >
> > Michael Ashton, CFA
> > Managing Principal
> >
> > Enduring Investments LLC
> > W: 973.457.4602
> > C: 551.655.8006
> > Schedule a Call: https://calendly.com/m-ashton
> >
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
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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.
> >
>
> ______________________________________________
> R-help using 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.
>

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