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rmatrixsparse-matrix

convert simple triplet matrix(slam) to sparse matrix(Matrix) in R

Is there a built-in function in either slam package or Matrix package to convert a sparse matrix in simple triplet matrix form (from slam package) to a sparse matrix in dgTMatrix/dgCMatrix form (from Matrix package) ?

And is there a built-in way to access non-zero entries from simple triplet matrix ?

I'm working in R

Solution

  • Actually, there is a built-in way:

    simple_triplet_matrix_sparse <-  sparseMatrix(i=simple_triplet_matrix_sparse$i, j=simple_triplet_matrix_sparse$j, x=simple_triplet_matrix_sparse$v,
           dims=c(simple_triplet_matrix_sparse$nrow, simple_triplet_matrix_sparse$ncol))

    From my own experience, this trick saved me tons of time and miseries, and computer crashing doing large-scale text mining using tm package. This question doesn't really need a reproducible example. A simple triplet matrix is a simple triplet matrix no matter what data it contains. This question is merely asking if there's a built-in function in either package to support conversion between the two.