Support kwargs only calls to contour

oscargus · oscargus · commit 1102fa27d357 · 2022-12-16T14:35:10.000+01:00
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -1386,7 +1386,7 @@ def _process_args(self, *args, corner_mask=None, algorithm=None, **kwargs):
         """
         Process args and kwargs.
         """
-        if isinstance(args[0], QuadContourSet):
+        if len(args) and isinstance(args[0], QuadContourSet):
             if self.levels is None:
                 self.levels = args[0].levels
             self.zmin = args[0].zmin
diff --git a/lib/matplotlib/tests/test_contour.py b/lib/matplotlib/tests/test_contour.py
@@ -693,3 +693,9 @@ def test_contour_remove():
     assert ax.get_children() != orig_children
     cs.remove()
     assert ax.get_children() == orig_children
+
+
+def test_countour_kwargsonly():
+    # Smoke test for GH#24743
+    # Passing only kwargs
+    plt.contour(Z=np.random.rand(30, 30))
