Build block matrix from existing matrixes and retain dimnames in r

Question

I'm building a block matrix with several smaller matrices that I past along the diagonal with the package Matrix

Let's say I have two matrices

m1=matrix(runif(10*10),nrow=10,ncol=10)
m2=matrix(runif(5*5),nrow=5,ncol=5)

I create a block matrix with

M<-bdiag(m1,m2)

How do I retain the names of columns and rows from the smaller m1 and m2 to the block matrix M?

note that I need M in a dataframe and therefore I also need at the end to run

M<-as.data.frame(as.matrix(M))

Thanks!

Answer 1

Add the dimnames back in after running bdiag (assuming you mean Matrix::bdiag):

m1 <- matrix(1:9,nrow=3,dimnames=list(LETTERS[1:3],LETTERS[1:3]))
m2 <- matrix(1:4,nrow=2,dimnames=list(LETTERS[4:5],LETTERS[4:5]))
m1

#  A B C
#A 1 4 7
#B 2 5 8
#C 3 6 9

m2
#  D E
#D 1 3
#E 2 4

out <- bdiag(m1,m2)
dimnames(out) <- Map(c, dimnames(m1), dimnames(m2))
out

#5 x 5 sparse Matrix of class "dgCMatrix"
#  A B C D E
#A 1 4 7 . .
#B 2 5 8 . .
#C 3 6 9 . .
#D . . . 1 3
#E . . . 2 4