R/plot_stacked_density.R

In DaanNieboer/DCTFmisc: Functions to Aid in Data Curation

#' Create a stacked stacked density chart
#'
#' @param x values for the density plot.
#' @param grp variable containing the membership to groups.
#' @param xlab label of the x-axis.
#' @param ylab label of the y-axis.
#' @param xlim plotting limits of the x-axis.
#' @param y_labels labels at the ticks of the y-axis.
#' @param mar A numeric vector which give the margin on the four sides of  the plot. For more detail \code{?par}.
#' @param mgp The margin line for the axis title, labels and line. For more detail \code{?par}.
#' @param tck The length of the tick marks. For more detail \code{?par}.
#' @param ... Further arguments passed to \code{par}.
#' @return A stacked density chart showing the density of \code{x} in the different groups contained in \code{grp}



plot_stacked_density <- function(x, grp, xlim = c(0, 1), xlab = "Value",
                                 ylab = "Group", y_labels = NULL,
                                 mar = c(3, 5, 2, 1), mgp = c(2,.7,0),
                                 tck = -.01,...){
  n_grp      <- length(unique(grp))
  unique_grp <- sort(unique(grp))
  if(is.null(y_labels)){
    y_labels <- unique_grp
  }
  if(length(unique_grp)!=length(y_labels)){
    stop("Nr. of groups not equal to the number of y_labels!")
  }

  dens_list <- list()

  par(mar = mar, mgp = mgp, tck = tck,...)
  plot(1, type = "n", xlim = xlim, ylim = c(1, n_grp + 2),
       axes = FALSE, xlab = xlab, ylab = ylab)

  for(i in 1:n_grp){
    dens <- density(x[grp==unique_grp[i]])
    max_y <- max(dens$y)
    lines(  dens$x, 0.8 * dens$y/max_y + i)
    polygon(dens$x, 0.8 * dens$y/max_y + i, col = rgb(0, 0, 0, 0.4), border = NA)
    abline(h = i, lwd = 0.5)
  }
  axis(1)
  axis(2, at = 1:n_grp, labels = y_labels,las = 2)
}