Fix #2467: multi-aesthetic scales and identity scale handling

Author: cpsievert

NEWS.md

@@ -30,6 +30,7 @@ See the [plotly.js releases page](https://github.com/plotly/plotly.js/releases)
 * Closed #2455, #2460: `ggplotly()` no longer creates empty shapes when `panel.border` is `element_blank()` (ggplot2 4.0.0 compatibility).
 * Closed #2466: `ggplotly()` no longer errors when `scale_*_manual()` has unused aesthetics (e.g., `aesthetics = c("colour", "fill")` when only colour is used).
 * Closed #2305: `ggplotly()` now respects `geom_boxplot(outlier.shape = NA)` to hide outlier points.
+* Closed #2467: `ggplotly()` now correctly shows legends and splits traces when scales have multiple aesthetics.
 
 # plotly 4.11.0
 

R/layers2traces.R

@@ -78,11 +78,16 @@ layers2traces <- function(data, prestats_data, layout, p) {
   }, data, hoverTextAes)
 
   # draw legends only for discrete scales
+  # Register each aesthetic separately for proper legend matching (fixes #2467)
+  # When a scale has multiple aesthetics (e.g., c("colour", "fill")), we need
+  # individual entries so "colour_plotlyDomain" matches discreteScales[["colour"]]
+  # Skip identity scales (guide = "none") as they don't produce legends or trace splitting
   discreteScales <- list()
   for (sc in p$scales$non_position_scales()$scales) {
-    if (sc$is_discrete()) {
-      nm <- paste(sc$aesthetics, collapse = "_")
-      discreteScales[[nm]] <- sc
+    if (sc$is_discrete() && !identical(sc$guide, "none")) {
+      for (aes_name in sc$aesthetics) {
+        discreteScales[[aes_name]] <- sc
+      }
     }
   }
   # Convert "high-level" geoms to their "low-level" counterpart

tests/testthat/_snaps/ggplot-boxplot/boxplot-fillcolor.svg

@@ -17,7 +17,25 @@ test_that("scale_*_manual with unused aesthetics does not error (#2466)", {
       aesthetics = c("colour", "fill")
     )
   # Should not error with "undefined columns selected"
-  # (Note: trace splitting with multi-aesthetic scales is a separate issue #2467)
   expect_error(plotly_build(ggplotly(p)), NA)
 })
 
+test_that("multi-aesthetic scales show legend and split traces correctly (#2467)", {
+  # When scale has aesthetics = c('colour', 'fill') and both are used,
+  # traces should be split by the variable and legend should appear
+  p <- ggplot(iris, aes(Sepal.Length, Sepal.Width, colour = Species, fill = Species)) +
+    geom_point(shape = 21) +
+    scale_colour_manual(
+      values = c("setosa" = "red", "versicolor" = "blue", "virginica" = "green"),
+      aesthetics = c("colour", "fill")
+    )
+  L <- plotly_build(ggplotly(p))$x
+  # Should have 3 traces (one per Species level)
+  expect_equal(length(L$data), 3)
+  # Should show legend
+  expect_true(any(sapply(L$data, function(d) isTRUE(d$showlegend))))
+  # Trace names should be the species names
+  trace_names <- sapply(L$data, function(d) d$name)
+  expect_true(all(c("setosa", "versicolor", "virginica") %in% trace_names))
+})
+