R/plot.scc_chart.R

In jakobbossek/scc: Shewart control charts in R.

#' Plot a SCC chart.
#'
#' @param x [\code{scc_chart}]\cr
#'   An object of type \code{scc_chart}.
#' @param ... [\code{list}]\cr
#'   Further params passed to plot function.
#'
#' @return
#'   Nothing. As a side-effect the chart is plotted.
#'
#' @export
plot.scc_chart = function(x, ...) {
	n_blocks = getNumberOfBlocks(x)
	bounds = x$bounds

	# add enough whitespace between plot border and control lines
	ylim_space = 0.1 * (max(bounds$UCB) - min(bounds$LCB))

	# draw polygon
	plot(1:n_blocks, x$y_value, type = "l",
		lwd = 2,
		main = x$description,
		xlab = "block",
		ylab = x$y_value_name,
		ylim = c(min(bounds$LCB) - ylim_space, max(bounds$UCB) + ylim_space),
		...
  )

	grid()
	# draw points of polygon
	points(1:n_blocks, x$y_value, pch = 19)
	# determine number of desired_value to place the label correctly
	y_value_pos = if (length(x$desired_value) == 1) x$desired_value else x$desired_value[n_blocks]
	if (length(x$desired_value) == 1) {
		abline(h = x$desired_value, col = "darkgray", lty = 5)
	} else {
		lines(1:n_blocks, x$desired_value, lty = 5)
	}

	mtext(x$desired_value_name, side = 4, at = c(n_blocks, y_value_pos), cex = 0.7, outer = FALSE, line = 1, las = 1)

	# draw control bounds
	if (length(bounds$UCB) == 1) {
		abline(h = bounds$UCB, lty = 5, lwd = 2, col = "tomato")
		abline(h = bounds$LCB, lty = 5, lwd = 2, col = "tomato")
	} else {
		lines(1:n_blocks, bounds$UCB, lty = 5, lwd = 2, col = "tomato")
		lines(1:n_blocks, bounds$LCB, lty = 5, lwd = 2, col = "tomato")
	}

	#draw control bounds
	if ("LWB" %in% names(bounds) && "UWB" %in% names(bounds)) {
		if (length(bounds$UWB) == 1) {
			abline(h = bounds$UWB, lty = 5, lwd = 2, col = "tomato2")
			abline(h = bounds$LWB, lty = 5, lwd = 2, col = "tomato2")
		}
	}
}