How do I convert a n*1 matrix to a n*n diagonal matrix

Question

I have a nx1 matrix I want to convert this to a nxn diagonal matrix in R

Answer 1

As @Ben Bolker has suggested, you can simply define your identity matrix using diag:

my.matrix <- diag(0.25, 4)
my.matrix
##      [,1] [,2] [,3] [,4]
## [1,] 0.25 0.00 0.00 0.00
## [2,] 0.00 0.25 0.00 0.00
## [3,] 0.00 0.00 0.25 0.00
## [4,] 0.00 0.00 0.00 0.25