How to convert a sparse matrix into a matrix of index and value of non-zero element

Question

We can construct a sparse matrix from an index and value of non-zero element with the sparseMatrix or spMatrix. Is there any function convert a spa

Answer 1

Use which with arr.ind:

idx <- which(A != 0, arr.ind=TRUE)
cbind(idx, A[idx])
#      [,1] [,2] [,3]
# [1,]    1    1    1
# [2,]    3    3    2
# [3,]    5    4    3