--- a
+++ b/R/DIscBIO-generic-plotGap.R
@@ -0,0 +1,30 @@
+#' @title Plotting Gap Statistics
+#' @export
+#' @rdname plotGap
+#' @param object \code{DISCBIO} class object.
+#' @param y_limits 2-length numeric vector with the limits for the gap plot
+#' @return A plot of the gap statistics
+setGeneric(
+  "plotGap", function(object, y_limits = NULL) standardGeneric("plotGap")
+)
+
+#' @rdname plotGap
+setMethod(
+  f = "plotGap",
+  signature = "DISCBIO",
+  definition = function(object, y_limits) {
+    if (length(object@kmeans$kpart) == 0) {
+      stop("run clustexp before plotgap")
+    }
+    gap <- object@kmeans$gap
+    if (is.null(y_limits)) {
+      y_lo <- min(gap$Tab[, "gap"]) - 1 * max(gap$Tab[, "SE.sim"])
+      y_up <- max(gap$Tab[, "gap"]) + 1 * max(gap$Tab[, "SE.sim"])
+      y_limits <- c(y_lo, y_up)
+    }
+    plot(
+      gap,
+      las = 1, ylim = y_limits, main = "Gap Statistics"
+    )
+  }
+)