R/plotDistance.R

In Ziegelsteintom/rmazing: Algorithms for Different Kinds of Perfect Mazes

#' Plot Method for a Distance Object
#'
#' Adds a rainbow colored interpretation of the distance matrix
#'
#' @param x a distance matrix
#' @param ... optional graphics parameter
#' @param alpha controls how bright the colors will be
#' @param startingpoint boolean, if TRUE it will plot the starting point of
#' of the distance matrix calculations
#'
#' @return NULL
#' @export
#'
#' @examples
#' maze <- makeMazeRecursiveBacktracker()
#' d <- distance(maze)
#' plot(maze)
#' plot(d)

plot.distance <- function(x, alpha = 0.3, startingpoint = TRUE, ...){

  w <- attributes(x)$width
  h <- attributes(x)$height
  # for some reason putting attr() inside the fct does not work
  s <- attributes(x)$start

  # Maximum distance
  m <- max(x)

  # Initialize result vector
  res <- vector(mode = "list", length = m)

  # Calculate Cells for all distances
  for(i in 1:m){
    res[[i]] <-  which(x == i, arr.ind = TRUE)
  }

  color <- grDevices::rainbow(m, alpha = alpha)

  # Loop over distances
  for(i in 1:m){

    # Cells with same distance
    for(k in 1:nrow(res[[i]])){
      x <- res[[i]][k,2]
      y <- h - res[[i]][k,1] + 1
      graphics::polygon(x = c(x, x+1, x+1, x),
                        y = c(y, y, y+1, y+1),
                        col = color[i], border = NA, ...)
    }
  }

  # Draw starting point
  if(startingpoint == TRUE){
    temp_coord <- coord_from_list_nr(s, w, h)
    xcoord <- temp_coord[2] + 0.5
    ycoord <- h + 1.5 - temp_coord[1]
    graphics::points(x = xcoord , y = ycoord, pch = 20)
  }
}