Displaying 1 result from an estimated 1 matches for "whereinrow".
2012 Oct 26
1
matrix algebra for constructing a special matrix?
Dear R-users,
would it be a better way to construct the matrix below without using any for-loop or model.matrix? preferably with some matrix algebra?
Thanks in advance,
Carlo Giovanni Camarda
## dimensions
m <- 3
n <- 4
mn <- m*n
k <- m+n-1
## with a for-loop
X <- matrix(0, mn, k)
for(i in 1:n){
wr <- 1:m+(i-1)*m
wc <- rev(1:m+(i-1))
where <- cbind(wr,wc)