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I need to make a matrix in R with its elements are from matrices I defined before. For example, I have 4 matrices, 

w <- matrix(c(1,2,3,4),2,2)
x <- matrix(c(5,6,7,8),2,2)
y <- matrix(c(9,10,11,12),2,2)
z <- matrix(c(13,14,15,16),2,2)

Then, the new matrix should be a 4X4 matrix with w is an [1:2,1:2] element, x is an [1:2,3:4] element, y is an [3:4,1:2] element, and z is an [3:4,3:4] element.

How can I do that quickly?

lmo
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Yohanes Eki Apriliawan
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1 Answers1

4

We can create an array and then loop through the third dimension, and rbind it.

ar1 <- array(c(w, x, y,z), dim=c(2, 4,2))
do.call(rbind,lapply(seq(dim(ar1)[3]), function(i) ar1[,,i]))
#     [,1] [,2] [,3] [,4]
#[1,]    1    3    5    7
#[2,]    2    4    6    8
#[3,]    9   11   13   15
#[4,]   10   12   14   16

Or as @thelatemail mentioned in the comments

apply(array(c(w,x,y,z), dim=c(2,4,2)), 2, I)

where I stands for inhibit interpretation or use identity in place of I

akrun
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