R help - Jul 2005 - A one-liner to create a 3-dim array

Hi,

 

I would like to write a one-line R code to create a 3-dim array, B, of
dimension (n,n,m) from a matrix, A, of dimension (m,n) such that the i-th
element of the 3-dim array, B[, , i]  is the outer product of the i-th row
of A.  

 

Thanks for any help,

Ravi.


	[[alternative HTML version deleted]]

B <- array(apply(A,1,function(x){x%o%x}),dim=c(nrow(A),dim(A)))

				cheers,

					Rolf Turner
					rolf at math.unb.ca

Ravi Varadhan wrote:
>  I would like to write a one-line R code to create a 3-dim array, B, of
>  dimension (n,n,m) from a matrix, A, of dimension (m,n) such that the i-th
>  element of the 3-dim array, B[, , i]  is the outer product of the i-th row
>  of A.

I think this works:

B <- aperm(rep(t(A),n)*rep(A,rep(n,n*m)), perm=c(1,3,2))

Reid Huntsinger

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Ravi Varadhan
Sent: Monday, July 25, 2005 1:39 PM
To: r-help at stat.math.ethz.ch
Subject: [R] A one-liner to create a 3-dim array


Hi,

 

I would like to write a one-line R code to create a 3-dim array, B, of
dimension (n,n,m) from a matrix, A, of dimension (m,n) such that the i-th
element of the 3-dim array, B[, , i]  is the outer product of the i-th row
of A.  

 

Thanks for any help,

Ravi.


	[[alternative HTML version deleted]]

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