Eric,
I am not sure your solution is particularly economical albeit it works for
arbitrary arrays of any dimension, presumably. But it seems to involve
converting a matrix to a tensor just to undo it back to a vector. Other
solutions offered here, simply manipulate the dim attribute of the data
structure.
Of course, the OP may have uses in mind which the package might make easier. We
often get fairly specific questions here without the additional context that may
help guide a better answer.
-----Original Message-----
From: R-help <r-help-bounces at r-project.org> On Behalf Of Eric Berger
Sent: Sunday, August 6, 2023 3:34 AM
To: Bert Gunter <bgunter.4567 at gmail.com>
Cc: R-help Mailing List <r-help at r-project.org>; Steven Yen <styen at
ntu.edu.tw>
Subject: Re: [R] Stacking matrix columns
Stacking columns of a matrix is a standard operation in multilinear
algebra, usually written as the operator vec().
I checked to see if there is an R package that deals with multilinear
algebra. I found rTensor, which has a function vec().
So, yet another way to accomplish what you want would be:
> library(rTensor)
> vec(as.tensor(x))
Eric
On Sun, Aug 6, 2023 at 5:05?AM Bert Gunter <bgunter.4567 at gmail.com>
wrote:>
> Or just dim(x) <- NULL.
> (as matrices in base R are just vectors with a dim attribute stored in
> column major order)
>
> ergo:
>
> > x
> [1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
> > x<- 1:20 ## a vector
> > is.matrix(x)
> [1] FALSE
> > dim(x) <- c(5,4)
> > is.matrix(x)
> [1] TRUE
> > attributes(x)
> $dim
> [1] 5 4
>
> > ## in painful and unnecessary detail as dim() should be used instead
> > attr(x, "dim") <- NULL
> > is.matrix(x)
> [1] FALSE
> > x
> [1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
>
> ## well, you get it...
>
> -- Bert
>
> On Sat, Aug 5, 2023 at 5:21?PM Iris Simmons <ikwsimmo at gmail.com>
wrote:
> >
> > You could also do
> >
> > dim(x) <- c(length(x), 1)
> >
> > On Sat, Aug 5, 2023, 20:12 Steven Yen <styen at ntu.edu.tw>
wrote:
> >
> > > I wish to stack columns of a matrix into one column. The
following
> > > matrix command does it. Any other ways? Thanks.
> > >
> > > > x<-matrix(1:20,5,4)
> > > > x
> > > [,1] [,2] [,3] [,4]
> > > [1,] 1 6 11 16
> > > [2,] 2 7 12 17
> > > [3,] 3 8 13 18
> > > [4,] 4 9 14 19
> > > [5,] 5 10 15 20
> > >
> > > > matrix(x,ncol=1)
> > > [,1]
> > > [1,] 1
> > > [2,] 2
> > > [3,] 3
> > > [4,] 4
> > > [5,] 5
> > > [6,] 6
> > > [7,] 7
> > > [8,] 8
> > > [9,] 9
> > > [10,] 10
> > > [11,] 11
> > > [12,] 12
> > > [13,] 13
> > > [14,] 14
> > > [15,] 15
> > > [16,] 16
> > > [17,] 17
> > > [18,] 18
> > > [19,] 19
> > > [20,] 20
> > > >
> > >
> > > ______________________________________________
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> ______________________________________________
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______________________________________________
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