[R] Multiplying a list of matrices with a vector
Mendolia, Franco
fmendolia at mcw.edu
Thu Sep 29 00:04:57 CEST 2011
Hi all!
I have a list of matrices and I want to multiply the ith element of the list with the ith element of a another vector. That is,
> LL <- list(A=diag(3),B=diag(3),C=diag(3))
> vec <- 1:3
> for(i in 1:3)
+ {
+ LL[[i]] <- LL[[i]]*vec[i]
+ }
> LL
$A
[,1] [,2] [,3]
[1,] 1 0 0
[2,] 0 1 0
[3,] 0 0 1
$B
[,1] [,2] [,3]
[1,] 2 0 0
[2,] 0 2 0
[3,] 0 0 2
$C
[,1] [,2] [,3]
[1,] 3 0 0
[2,] 0 3 0
[3,] 0 0 3
Is there another (more efficient) way of doing this without using loops? I found an older entry in this list with a similar problem, where the list elements were always multiplied with the same number, e.g., lapply(LL, function(x) x*3) and I was looking for something similar.
Best,
Franco
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