Preserve aesthetics in colourbar merge (#5328)

* Preserve aesthetics in colourbar merge

NEWS.md

@@ -77,6 +77,8 @@
  * `guide_coloursteps()` and `guide_bins()` sort breaks (#5152).
  * `guide_axis()` gains a `cap` argument that can be used to trim the
  axis line to extreme breaks (#4907).
+ * `guide_colourbar()` and `guide_coloursteps()` merge properly when one
+ of aesthetics is dropped (#5324).
  * Fixed regression in `guide_legend()` where the `linewidth` key size
  wasn't adapted to the width of the lines (#5160).
 

R/guide-colorbar.R

@@ -376,6 +376,8 @@ GuideColourbar <- ggproto(
  },
 
  merge = function(self, params, new_guide, new_params) {
+ new_params$key$.label <- new_params$key$.value <- NULL
+ params$key <- vec_cbind(params$key, new_params$key)
  return(list(guide = self, params = params))
  },
 

tests/testthat/test-guides.R

@@ -307,6 +307,27 @@ test_that("guide_coloursteps and guide_bins return ordered breaks", {
  expect_true(all(diff(key$.value) < 0))
 })
 
+
+test_that("guide_colourbar merging preserves both aesthetics", {
+ # See issue 5324
+
+ scale1 <- scale_colour_viridis_c()
+ scale1$train(c(0, 2))
+
+ scale2 <- scale_fill_viridis_c()
+ scale2$train(c(0, 2))
+
+ g <- guide_colourbar()
+ p <- g$params
+
+ p1 <- g$train(p, scale1, "colour")
+ p2 <- g$train(p, scale2, "fill")
+
+ merged <- g$merge(p1, g, p2)
+
+ expect_true(all(c("colour", "fill") %in% names(merged$params$key)))
+})
+
 test_that("guide_colourbar warns about discrete scales", {
 
  g <- guide_colourbar()
@@ -315,6 +336,7 @@ test_that("guide_colourbar warns about discrete scales", {
 
  expect_warning(g <- g$train(g$params, s, "colour"), "needs continuous scales")
  expect_null(g)
+
 })
 
 # Visual tests ------------------------------------------------------------