Add viridis examples based on the brewer examples

Author: karawoo

R/scale-viridis.r

@@ -13,6 +13,35 @@
 #' @family colour scales
 #' @rdname scale_viridis
 #' @export
+#' @examples
+#' dsamp <- diamonds[sample(nrow(diamonds), 1000), ]
+#' (d <- ggplot(dsamp, aes(carat, price)) +
+#'   geom_point(aes(colour = clarity)))
+#' d + scale_colour_viridis_d()
+#'
+#' # Change scale label
+#' d + scale_colour_viridis_d("Diamond\nclarity")
+#'
+#' # Select palette to use, see ?scales::viridis_pal for more details
+#' d + scale_colour_viridis_d(option = "plasma")
+#' d + scale_colour_viridis_d(option = "inferno")
+#'
+#' \donttest{
+#' # scale_fill_viridis_d works just the same as
+#' # scale_colour_viridis_d but for fill colours
+#' p <- ggplot(diamonds, aes(x = price, fill = cut)) +
+#'   geom_histogram(position = "dodge", binwidth = 1000)
+#' p + scale_fill_viridis_d()
+#' # the order of colour can be reversed
+#' p + scale_fill_viridis_d(direction = -1)
+#' }
+#'
+#' # Use viridis_c with continous data
+#' v <- ggplot(faithfuld) +
+#'   geom_tile(aes(waiting, eruptions, fill = density))
+#' v
+#' v + scale_fill_viridis_c()
+#' v + scale_fill_viridis_c(option = "plasma")
 scale_colour_viridis_d <- function(..., alpha = 1, begin = 0, end = 1,
                                    direction = 1, option = "D") {
   discrete_scale(