Block diagonal matrices in R
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As far as I can tell, R doesn’t have a function for building block diagonal matrices so as I needed one, I’ve coded it myself. It might save someone some time.
Example:
Let m1 and m2 two square matrices.
By passing any number of matrices as argument:
Or a list of matrices:
It produces:
Selec All Code:
1 2 | colourScale<-seq(0,1,length.out=100) image(blockMatrix[30:1,],asp=1,col=rgb(colourScale,colourScale,colourScale),ann=FALSE,xaxt="n",yaxt="n",axes=FALSE) |
That is, a matrix which is zero everywhere but with m1,m2,m2 and m1 on the diagonal.
Code:
Selec All Code:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | # builds a block matrix whose diagonals are the square matrices provided.
# m1=matrix(runif(10*10),nrow=10,ncol=10)
# m2=matrix(runif(5*5),nrow=5,ncol=5)
# blockMatrix<-blockMatrixDiagonal(m1,m2,m2,m1)
# or
# blockMatrix<-blockMatrixDiagonal(list(m1,m2,m2,m1))
# C.Ladroue
blockMatrixDiagonal<-function(...){
matrixList<-list(...)
if(is.list(matrixList[[1]])) matrixList<-matrixList[[1]]
dimensions<-sapply(matrixList,FUN=function(x) dim(x)[1])
finalDimension<-sum(dimensions)
finalMatrix<-matrix(0,nrow=finalDimension,ncol=finalDimension)
index<-1
for(k in 1:length(dimensions)){
finalMatrix[index:(index+dimensions[k]-1),index:(index+dimensions[k]-1)]<-matrixList[[k]]
index<-index+dimensions[k]
}
finalMatrix
} |
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