R/fasterscale.R

In liangyy/fasterscale: Methods for Efficiently Centering and Scaling Matrices

#' @title Fast Centering and Scaling of Matrices
#' 
#' @description Does the same thing as \code{scale(x)}, but faster.
#' 
#' @details Uses \code{\link[matrixStats]{colSds}} from the 
#' \code{matrixStats} package.
#' 
#' @param x A numeric matrix; \code{is.matrix(x)} should be \code{TRUE}.
#'
#' @return A matrix in which the columns are centered to have zero mean,
#' and they are also scaled to have standard deviation of 1. 
#'
#' @importFrom matrixStats colSds
#' @importFrom Rcpp evalCpp
#'
#' @useDynLib fasterscale
#'
#' @export 
scale_faster = function (x) {
  a <- colMeans(x)
  b <- colSds(x)
  # x <- t(t(x) - a)
  # x <- t(t(x) / b)
  scale_rcpp(x, a, b)
  cat('Done')
  return(x)
}