R/read_in_and_save.R

In Osburg/eigenfaces: PCA on Eigenfaces

#library(tidyverse)
#library(imager)

#' Load any dataset
#'
#' Makes it possible to not only load .csv files (as in the case of the Olivetti
#' Dataset) but also to load seperate .png, .jpeg or .bmp files as an imageset.
#'
#' @param folderpath str, relative path to the folder (incl. the foldername)
#' @param filetype str, lower letter filetype
#'
#' @return td, List of arrays. Training Data.
#' @export
#'
#' @examples
#' folder <- system.file("extdata","testfiles",package="eigenfaces")
#' td <- load_any_imageset(folder, "jpg")
load_any_imageset <- function(folderpath, filetype) {
  stopifnot("folderpath does not exist" = file.exists(folderpath))
  stopifnot("folderpath must be of length 1" = length(folderpath)==1)
  stopifnot("filetype not supported (please use lowercase letters)"
            = filetype %in% c("jpg", "png", "jpeg", "bmp"))

  filepath <- paste(folderpath, "/",
                     list.files(path = folderpath, pattern=paste("*.",filetype,sep="")),
                     sep = "")

  # Creates object of the class imageset_ef
  td <- list()
  class(td) <- "imageset_ef"

  # Puts images in the imageset_ef object
  cnt <- 1
  for (fp in filepath) {
    im <- load.image(fp)

    # Turn RGB into grayscale
    if (dim(im)[4]==3) {
      im <- grayscale(im)
    }

    class(im) <- "image_ef"
    td[[cnt]] <- im[,,1,1]
    class(td[[cnt]]) <- "image_ef"
    cnt <- cnt+1
  }
  td
}



#' Save image
#'
#' Save any suitable array as image.
#'
#' @param im arr, array-like structure
#' @param filename str, working names
#' @param filetype str, "jpg", "jpeg" or "png"
#' @param path str, optional. Default is current wd.
#'
#' @return the image is saved.
#' @export
#'
#' @examples
#' folder <- system.file("extdata","testfiles",package="eigenfaces")
#' td <- load_any_imageset(folder, "jpg")
#' save_image_ef(td[[3]], "test_save", "jpg", path = folder)
save_image_ef <- function(im, filename, filetype, path = NULL) {
  stopifnot("im must be of class 'image_ef'" = is.image_ef(im))
  stopifnot("im must be at least of length 1" = length(im)>0)
  stopifnot("folderpath does not exist" = file.exists(path))
  stopifnot("filename must be of length 1" = length(filename)==1)
  stopifnot("filetype not supported (please use lowercase letters)"
            = filetype %in% c("jpg", "png", "jpeg"))

  # Turn array into cimg for library imager
  dim(im) <- c(dim(im), 1, 1)
  im <- as.cimg(unclass(im))

  if (is.null(path)) {
    save.image(im, paste(filename, ".", filetype, sep = ""))
  }
  else {
    save.image(im, paste(path, "/", filename, ".", filetype, sep = ""))
  }
}