allow size and linetype aesthetics in geom_dotplot (#3078)

* fix #3059

* Change 'size' aesthetic to 'stroke' in geom_dotplot

* code review changes for @clauswilke

* one last change for code review

Author: paleolimbot

R/geom-dotplot.r

@@ -83,6 +83,9 @@
 #' # Expand dot diameter
 #' ggplot(mtcars, aes(x = mpg)) + geom_dotplot(binwidth = 1.5, dotsize = 1.25)
 #'
+#' # Change dot fill colour, stroke width
+#' ggplot(mtcars, aes(x = mpg)) + geom_dotplot(binwidth = 1.5, fill = "white", stroke = 2)
+#'
 #' \donttest{
 #' # Examples with stacking along y axis instead of x
 #' ggplot(mtcars, aes(x = 1, y = mpg)) +
@@ -175,7 +178,7 @@ GeomDotplot <- ggproto("GeomDotplot", Geom,
   required_aes = c("x", "y"),
   non_missing_aes = c("size", "shape"),
 
-  default_aes = aes(colour = "black", fill = "black", alpha = NA),
+  default_aes = aes(colour = "black", fill = "black", alpha = NA, stroke = 1, linetype = "solid"),
 
   setup_data = function(data, params) {
     data$width <- data$width %||%
@@ -276,7 +279,8 @@ GeomDotplot <- ggproto("GeomDotplot", Geom,
                   stackposition = tdata$stackpos, stackratio = stackratio,
                   default.units = "npc",
                   gp = gpar(col = alpha(tdata$colour, tdata$alpha),
-                            fill = alpha(tdata$fill, tdata$alpha)))
+                            fill = alpha(tdata$fill, tdata$alpha),
+                            lwd = tdata$stroke, lty = tdata$linetype))
     )
   },
 

man/geom_dotplot.Rd

@@ -177,6 +177,21 @@ test_that("geom_dotplot draws correctly", {
     ggplot(dat2, aes(as.numeric(x), y)) + geom_dotplot(binwidth = .2, binaxis = "y", stackdir = "center")
   )
 
+  # border width and size
+  expect_doppelganger(
+    "variable linetype and size work when specified as aesthetics",
+    ggplot(
+      dat,
+      aes(
+        x,
+        linetype = rep(c("a", "b"), length.out = nrow(dat)),
+        stroke = rep(c(1, 2), length.out = nrow(dat))
+      )
+    ) +
+      geom_dotplot(binwidth = .4, fill = "red", col = "blue") +
+      continuous_scale("stroke", "scaleName", function(x) scales::rescale(x, to = c(1, 6)))
+  )
+
   # Stacking groups
   expect_doppelganger("stackgroups with 3 groups, dot-density with aligned bins",
     ggplot(dat2, aes(y, fill = x)) + geom_dotplot(binwidth = .25, stackgroups = TRUE, binpositions = "all", alpha = 0.5)