Only sort numeric breaks in binned guides (#5758)

* only sort numeric breaks

* add test

* add news bullet

Author: teunbrand

NEWS.md

@@ -15,6 +15,9 @@
 * Patterns and gradients are now also enabled in `geom_sf()` 
   (@teunbrand, #5716).
 * `stat_bin()` deals with non-finite breaks better (@teunbrand, #5665).
+* Fixed bug in `guide_bins()` and `guide_coloursteps()` where discrete breaks,
+  such as the levels produced by `cut()`, were ordered incorrectly 
+  (@teunbrand, #5757).
 * Theme elements that do not exist now throw warnings instead of errors (#5719).
 * Fixed bug in `coord_radial()` where full circles were not treated as such 
   (@teunbrand, #5750).

R/guide-bins.R

@@ -333,8 +333,9 @@ parse_binned_breaks = function(scale, breaks = scale$get_breaks(),
   if (length(breaks) == 0) {
     return(NULL)
   }
-  breaks <- sort(breaks)
+
   if (is.numeric(breaks)) {
+    breaks <- sort(breaks)
     limits <- scale$get_limits()
     if (!is.numeric(scale$breaks)) {
       breaks <- breaks[!breaks %in% limits]

tests/testthat/test-guides.R

@@ -501,6 +501,34 @@ test_that("empty guides are dropped", {
   expect_equal(lengths(guides, use.names = FALSE), rep(0, 5))
 })
 
+test_that("bins can be parsed by guides for all scale types", {
+
+  breaks <- c(90, 100, 200, 300)
+  limits <- c(0, 1000)
+
+  sc <- scale_colour_continuous(breaks = breaks)
+  sc$train(limits)
+
+  expect_equal(parse_binned_breaks(sc)$breaks, breaks)
+
+  sc <- scale_colour_binned(breaks = breaks)
+  sc$train(limits)
+
+  expect_equal(parse_binned_breaks(sc)$breaks, breaks)
+
+  # Note: discrete binned breaks treats outer breaks as limits
+  cut <- cut(c(0, 95, 150, 250, 1000), breaks = breaks)
+
+  sc <- scale_colour_discrete()
+  sc$train(cut)
+
+  parsed <- parse_binned_breaks(sc)
+  expect_equal(
+    sort(c(parsed$limits, parsed$breaks)),
+    breaks
+  )
+})
+
 # Visual tests ------------------------------------------------------------
 
 test_that("axis guides are drawn correctly", {