R/dotPlotStack.R

In openintro: Data Sets and Supplemental Functions from 'OpenIntro' Textbooks and Labs

#' Add a Stacked Dot Plot to an Existing Plot
#'
#' Add a stacked dot plot to an existing plot. The locations for the points in
#' the dot plot are returned from the function in a list.
#'
#'
#' @param x A vector of numerical observations for the dot plot.
#' @param radius The approximate distance that should separate each point.
#' @param seed A random seed (integer). Different values will produce different
#' variations.
#' @param addDots Indicate whether the points should be added to the plot.
#' @param \dots Additional arguments are passed to
#' \code{\link[graphics]{points}}.
#' @return Returns a list with a height that can be used as the upper bound of
#' ylim for a plot, then also the x- and y-coordinates of the points in the
#' stacked dot plot.
#' @author David Diez
#' @seealso \code{\link{dotPlot}}, \code{\link{histPlot}}
#' @keywords stacked dot plot dot plot
#' @export
#' @examples
#'
#' #
dotPlotStack <- function(x, radius = 1, seed = 1, addDots = TRUE, ...) {
  set.seed(seed)
  x <- sample(x)
  y <- rep(NA, length(x))
  y[1] <- 1
  for (i in 2:length(x)) {
    add <- TRUE
    for (s in seq(radius, i * radius, radius / 20)) {
      these <- 1:(i - 1)
      dx <- (x[i] - x[these])^2
      dy <- (s - y[these])^2
      if (any(dx + dy < radius^2) || !add) {
        next
      } else {
        if (addDots) {
          graphics::points(x[i], s, ...)
        }
        y[i] <- s
        add <- FALSE
      }
    }
  }
  invisible(list(max(y) + radius, x, y))
}