FIX: Guard against already removed labels in ContourSet.remove()

buddy0452004 · buddy0452004 · commit d1575870cb14 · 2026-04-01T12:19:43.000+05:30
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -513,9 +513,12 @@ def labels(self, inline, inline_spacing):
                 self._paths[icon] = Path.make_compound_path(*additions)
 
     def remove(self):
+        axes = self.axes
         super().remove()
-        for text in self.labelTexts:
-            text.remove()
+        for text in list(self.labelTexts):
+            if axes is not None and text in axes.texts:
+                text.remove()
+        self.labelTexts.clear()
 
 
 def _find_closest_point_on_path(xys, p):
diff --git a/lib/matplotlib/tests/test_contour.py b/lib/matplotlib/tests/test_contour.py
@@ -876,3 +876,18 @@ def test_contour_aliases(fig_test, fig_ref):
 def test_contour_singular_color():
     with pytest.raises(TypeError):
         plt.figure().add_subplot().contour([[0, 1], [2, 3]], color="r")
+
+def test_contour_remove_after_label_removed():
+    # Test that CS.remove() works even if labels were manually removed first
+    # Regression test for https://github.com/matplotlib/matplotlib/issues/31404
+    fig, ax = plt.subplots()
+    x = np.linspace(-3.0, 3.0, 20)
+    y = np.linspace(-2.0, 2.0, 20)
+    X, Y = np.meshgrid(x, y)
+    Z = np.exp(-X**2 - Y**2)
+    CS = ax.contour(X, Y, Z)
+    labels = ax.clabel(CS, colors='k')
+    for label in labels:
+        label.remove()
+    ax.clabel(CS, colors='r')
+    CS.remove()  # Should not raise ValueError
