R/matrixToImages.R

In stnava/ANTsR: ANTs in R: Quantification Tools for Biomedical Images

#' Convert rows of a matrix to images
#'
#' Unmasks rows of a matrix and writes as images.
#'
#'
#' @param dataMatrix A matrix such as that created by \code{imagesToMatrix}.
#' @param mask An \code{antsImage} containing a binary mask.
#' Rows of the matrix
#' are unmasked and written as images. The mask defines the output image space.
#' @author Cook PA
#' @seealso \code{\link{imagesToMatrix}, \link{getMask}}
#' @examples
#' \dontrun{
#' # mat = matrixToImages( aMat, mask )
#' }
#'
#' @export matrixToImages
matrixToImages <- function(dataMatrix, mask) {
  # Writes rows of a matrix to 3D images.  mask should be an antsImage of the
  # correct dimensions and physical space
  mask <- check_ants(mask)
  error_not_antsImage(mask, "mask")

  numImages <- nrow(dataMatrix)
  numVoxelsInMatrix <- ncol(dataMatrix)
  numVoxelsInMask <- sum(mask > 0.5)
  if (numVoxelsInMatrix != numVoxelsInMask) {
    stop(paste(
      "Number of masked voxels", numVoxelsInMask, " do not match data",
      numVoxelsInMatrix
    ))
  }
  imagelist <- list()
  for (i in 1:numImages) {
    img <- antsImageClone(mask)
    img[mask > 0.5] <- dataMatrix[i, ]
    imagelist[[i]] <- img
  }
  return(imagelist)
}