[R] function to find coodinates in an array

[Henrik Bengtsson]

See arrayIndex() in the R.utils package, e.g.

X <- array((2*3*4):1, dim=c(2,3,4))
idx <- 1:length(X)
ijk <- arrayIndex(idx, dim=dim(X))
print(ijk)

     [,1] [,2] [,3]
[1,]    1    1    1
[2,]    2    1    1
[3,]    1    2    1
[4,]    2    2    1
[5,]    1    3    1
[6,]    2    3    1
[7,]    1    1    2
[8,]    2    1    2
[9,]    1    2    2
10,]    2    2    2
11,]    1    3    2
12,]    2    3    2
13,]    1    1    3
14,]    2    1    3
15,]    1    2    3
16,]    2    2    3
17,]    1    3    3
18,]    2    3    3
19,]    1    1    4
20,]    2    1    4
21,]    1    2    4
22,]    2    2    4
23,]    1    3    4
24,]    2    3    4

/Henrik

On 8/16/07, Moshe Olshansky <m_olshansky at yahoo.com> wrote:
> A not very good solution is as below:
>
> If your array's dimensions were KxMxN and the "linear"
> index is i then
> n <- ceiling(i/(K*M))
> i1 <- i - (n-1)*(K*M)
> m <- ceiling(i1/K)
> k <- i1 - (m-1)*K
>
> and your index is (k,m,n)
>
> I am almost sure that there is a function in R which
> does this (it exists in Matlab).
>
> Regards,
>
> Moshe.
>
> --- Ana Conesa <aconesa at ochoa.fib.es> wrote:
>
> > Dear list,
> >
> > I am looking for a function/way to get the array
> > coordinates of given
> > elements in an array. What I mean is the following:
> > - Let X be a 3D array
> > - I find the ordering of the elements of X by ord <-
> > order(X) (this
> > returns me a vector)
> > - I now want to find the x,y,z coordinates of each
> > element of ord
> >
> > Can anyone help me?
> >
> > Thanks!
> >
> > Ana
> >
> > ______________________________________________
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> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained,
> > reproducible code.
> >
>
> ______________________________________________
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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.
>