R/statistics.R

In neuroconductor-releases/Rvision: Basic Computer Vision Library

### Define generic statistics methods ###

# See zzz.R

#' @title Maxima and Minima of an Image
#'
#' @aliases max.Rcpp_Image
#'
#' @description Returns the maximum and minimum pixel values of an
#'  \code{\link{Image}} object. If the \code{\link{Image}} object has more than
#'  one channel, it returns the maximum and minimum of each channel.
#'
#' @param x An \code{\link{Image}} object.
#'
#' @param ... Unused at the moment.
#'
#' @return A numeric value for single-channel images; a matrix for multi-channels
#'  images.
#'
#' @author Simon Garnier, \email{garnier@@njit.edu}
#'
#' @seealso \code{\link{Image}}, \code{\link{minMaxLoc}}.
#'
#' @examples
#' # TODO
#'
#' @export
min.Rcpp_Image <- function(x, ...) {
  if (!isImage(x))
    stop("This is not an Image object.")

  switch (nchan(x),
          `_min`(x),
          NA,
          matrix(sapply(split(x), `_min`), nrow = 1, ncol = 3,
                 dimnames = list(c("val"), c("B", "G", "R"))),
          matrix(sapply(split(x), `_min`), nrow = 1, ncol = 4,
                 dimnames = list(c("val"), c("B", "G", "R", "A"))),
          NA
  )
}


#' @rdname min.Rcpp_Image
#' @export
max.Rcpp_Image <- function(x, ...) {
  if (!isImage(x))
    stop("This is not an Image object.")

  switch(nchan(x),
         `_max`(x),
         NA,
         matrix(sapply(split(x), `_max`), nrow = 1, ncol = 3,
                dimnames = list(c("val"), c("B", "G", "R"))),
         matrix(sapply(split(x), `_max`), nrow = 1, ncol = 4,
                dimnames = list(c("val"), c("B", "G", "R", "A"))),
         NA
  )
}


#' @title Coordinates of the Maxima and Minima of an Image
#'
#' @description \code{minMaxLoc} returns the maximum and minimum pixel values of
#'  an \code{\link{Image}} object, as well as their coordinates in the image. If
#'  the \code{\link{Image}} object has more than one channel, it returns the
#'  values for each channel.
#'
#' @param x An \code{\link{Image}} object.
#'
#' @return A matrix (or a list of matrices for multi-channels images).
#'
#' @author Simon Garnier, \email{garnier@@njit.edu}
#'
#' @seealso \code{\link{Image}}, \code{\link{min.Rcpp_Image}}, \code{\link{max.Rcpp_Image}}.
#'
#' @examples
#' # TODO
#'
#' @export
minMaxLoc <- function(x) {
  if (!isImage(x))
    stop("This is not an Image object.")

  switch(nchan(x),
         `_minMaxLoc`(x),
         NA,
         lapply(split(x), `_minMaxLoc`),
         lapply(split(x), `_minMaxLoc`),
         NA
  )
}