R/sparse_to_dense_matrix.R

In matthewjdenny/SpeedReader: High Performance Text Analysis

#' A function to convert a slam::simple_triplet_matrix sparse matrix object to a dense matrix object.
#'
#' @param sparse_matrix A sparse matrix object generated by the slam library.
#' @return A dense matrix
#' @export
sparse_to_dense_matrix <- function(sparse_matrix){
    nr <- sparse_matrix$nrow
    nc <- sparse_matrix$ncol
    ## old line: y <- matrix(vector(typeof(x$v), nr * nc), nr, nc)
    y <- matrix(0, nr, nc)  ##
    y[cbind(sparse_matrix$i, sparse_matrix$j)] <- sparse_matrix$v
    dimnames(y) <- sparse_matrix$dimnames
    return(y)
}