R/rowLogSumExps.R

In HenrikBengtsson/matrixStats: Functions that Apply to Rows and Columns of Matrices (and to Vectors)

#' Accurately computes the logarithm of the sum of exponentials across rows or
#' columns
#'
#' Accurately computes the logarithm of the sum of exponentials across rows or
#' columns.
#'
#' @inheritParams rowAlls
#' @inheritParams logSumExp
#'
#' @param lx A \code{\link[base]{numeric}} NxK \code{\link[base]{matrix}}.
#' Typically \code{lx} are \eqn{log(x)} values.
#'
#' @param rows,cols A \code{\link[base]{vector}} indicating subset of rows
#' (and/or columns) to operate over. If \code{\link[base]{NULL}}, no subsetting
#' is done.
#'
#' @param na.rm If \code{\link[base:logical]{TRUE}}, any missing values are
#' ignored, otherwise not.
#'
#' @param dim. An \code{\link[base]{integer}} \code{\link[base]{vector}} of
#' length two specifying the dimension of \code{x}, also when not a
#' \code{\link[base]{matrix}}.
#'
#' @param ... Not used.
#'
#' @return A \code{\link[base]{numeric}} \code{\link[base]{vector}} of length N
#' (K).
#'
#' @section Benchmarking:
#' These methods are implemented in native code and have been optimized for
#' speed and memory.
#'
#' @author Native implementation by Henrik Bengtsson.  Original R code by
#' Nakayama ??? (Japan).
#'
#' @seealso To calculate the same on vectors, \code{\link{logSumExp}}().
#'
#' @keywords array
#' @export
rowLogSumExps <- function(lx, rows = NULL, cols = NULL, na.rm = FALSE,
                          dim. = dim(lx), ..., useNames = TRUE) {
  if (is.na(useNames)) deprecatedUseNamesNA()
  has_na <- TRUE
  .Call(C_rowLogSumExps, lx, dim., rows, cols, na.rm, has_na, TRUE, useNames)
}


#' @rdname rowLogSumExps
#' @export
colLogSumExps <- function(lx, rows = NULL, cols = NULL, na.rm = FALSE,
                          dim. = dim(lx), ..., useNames = TRUE) {
  if (is.na(useNames)) deprecatedUseNamesNA()
  has_na <- TRUE
  .Call(C_rowLogSumExps, lx, dim., rows, cols, na.rm, has_na, FALSE, useNames)
}