Create matrix with diagonal element is matrix in r

Question

I have a 2X2 matrix, for instance A=matrix(1:4,2,2). With this matrix, I want to build matrix whose diagonal element is A like below. This example has just three A but I would like to make matrix with n diagonal element of matrix A

|A  0  0|
|0  A  0|
|0  0  A|

`n <- 3; nr <- nrow(A); ii <- vapply(1:n, function(x) row(A) + (x - 1L) * nr, integer(nr ^ 2)); \`[<-\`(matrix(0, nr * n, nr * n), cbind(c(ii), sort(ii)), rep(A, n))` will work for square matrices. — rawr, Apr 10 '16 at 04:34

score 0 · Answer 1 · answered Apr 10 '16 at 02:42

0

Here is a recursive solution:

CreateDiag<-function(n){
 if (n==1) {
    return(A)
 } else{
    A_2<-CreateDiag(n-1)
    temp1<-cbind(A_2,matrix(0,nrow = nrow(A_2),ncol = ncol(A)))
    temp2<-rbind(temp1,cbind(matrix(0,nrow = nrow(A),ncol = ncol(A_2)),A))
    return(temp2)
 }
}

(n is the number of blocks you want)

answered Apr 10 '16 at 02:42

adaien

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Once I tried n=1600, I got this error message – John legend2 Apr 10 '16 at 04:45
Error: evaluation nested too deeply: infinite recursion / options(expressions=)? – John legend2 Apr 10 '16 at 04:46
do you know how to do it? – John legend2 Apr 10 '16 at 04:46
and, I executed options(expressions=10000), and I did again CreateDiag(1600). but it takes too much time. can you give any solution? – John legend2 Apr 10 '16 at 04:48

score 0 · Answer 2 · answered Apr 10 '16 at 04:40

0

> DiagonalMatrix <- function(n, x) `diag<-`(matrix(0, n, n), x)
> DiagonalMatrix(2, 10)
     [,1] [,2]
[1,]   10    0
[2,]    0   10

answered Apr 10 '16 at 04:40

hatmatrix

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Create matrix with diagonal element is matrix in r

2 Answers2