Fix issue #3273

Author: benjeffery

python/CHANGELOG.rst

@@ -51,7 +51,11 @@
   "self" comparisons for `TreeSequence.genetic_relatedness`. This changes the
   error code returned in some situations.
   (:user:`andrewkern`, :user:`petrelharp`, :pr:`3235`, :issue:`3055`)
-  
+
+- Fix ``UnboundLocalError`` in ``draw_svg()`` when using numeric ``max_time``
+  values with mutations over roots.
+  (:user:`benjeffery`, :pr:`3274`, :issue:`3273`)
+
 
 **Breaking changes** 
 

python/tests/test_drawing.py

@@ -1868,6 +1868,22 @@ def test_min_ts_time(self):
         svg3 = ts.draw_svg(min_time=min(ts.tables.nodes.time), y_axis=True)
         assert svg2 == svg3
 
+    def test_numeric_max_time_with_mutations_over_roots(self):
+        t = self.get_mutations_over_roots_tree()
+        max_time_value = 10.0  # Use a numeric max_time value
+
+        with pytest.warns(
+            UserWarning, match="Mutations .* are above nodes which are not present"
+        ):
+            svg = t.draw_svg(max_time=max_time_value)
+        self.verify_basic_svg(svg)
+
+        with pytest.warns(
+            UserWarning, match="Mutations .* are above nodes which are not present"
+        ):
+            svg_log = t.draw_svg(max_time=max_time_value, time_scale="log_time")
+        self.verify_basic_svg(svg_log)
+
     #
     # TODO: update the tests below here to check the new SVG based interface.
     #

python/tskit/drawing.py

@@ -2003,6 +2003,8 @@ def assign_y_coordinates(
                 max_node_height = self.ts.max_root_time
                 max_mut_height = np.nanmax(np.append(mut_time, 0))
                 max_time = max(max_node_height, max_mut_height)  # Reuse variable
+            else:
+                max_node_height = max(self.node_height.values())
             if min_time == "tree":
                 min_time = min(self.node_height.values())
                 # don't need to check mutation times, as they must be above a node