fix: mapping to missing value(s) to shape

Author: has2k1

doc/changelog.qmd

@@ -25,6 +25,10 @@ title: Changelog
 
 - Fixed rendering of SVGs in jupyter notebooks.
 
+- Fixed [](:class:`~plotnine.geom_legend`) to show an empty key for
+  [](:class:`~plotnine.geom_point`) when the shape is mapped to variable with missing
+  values.
+
 ## v0.15.3
 (2025-01-28)
 

plotnine/guides/guide_legend.py

@@ -272,9 +272,12 @@ def draw(self):
         # Drawings
         drawings: list[ColoredDrawingArea] = []
         for i in range(nbreak):
-            da = ColoredDrawingArea(
-                elements.key_widths[i], elements.key_heights[i], 0, 0
-            )
+            try:
+                w, h = elements.key_widths[i], elements.key_heights[i]
+            except IndexError:
+                w, h = elements.empty_key_size
+
+            da = ColoredDrawingArea(w, h, 0, 0)
 
             # overlay geoms
             for params in self._layer_parameters:
@@ -482,3 +485,14 @@ def key_heights(self) -> list[float]:
         if self.is_horizontal:
             return [max(hs)] * len(hs)
         return hs
+
+    @cached_property
+    def empty_key_size(self) -> tuple[float, float]:
+        """
+        Size of an empty key
+        """
+        return (
+            (max(self.key_widths), min(self.key_heights))
+            if self.is_vertical
+            else (min(self.key_widths), max(self.key_heights))
+        )

tests/baseline_images/test_guide_internals/guide_legend_missing_value_for_shapes.png

@@ -41,3 +41,9 @@ def alphen(series, a):
     )
 
     assert p == "guide_legend_after_scale"
+
+
+def test_guide_legend_missing_value_for_shapes():
+    data = pd.DataFrame({"a": [1, 2, 3], "b": ["a", None, "z"]})
+    p = ggplot(data, aes("a", "b")) + geom_point(aes(shape="b"), na_rm=True)
+    assert p == "guide_legend_missing_value_for_shapes"