Don't warn on grid removal deprecation is grid is hidden

timhoffm · timhoffm · commit 9e6d7238b7ce · 2022-01-22T14:30:15.000+01:00
Fixes #21723. See #21723 (comment) for a full desciption of motivation and edge cases.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -5624,8 +5624,11 @@ def _interp_grid(X):
         return X, Y, C, shading
 
     def _pcolor_grid_deprecation_helper(self):
-        if any(axis._major_tick_kw["gridOn"]
-               for axis in self._get_axis_list()):
+        grid_active = any(axis._major_tick_kw["gridOn"]
+                          for axis in self._get_axis_list())
+        # explicit is-True check because get_axisbelow() can also be 'line'
+        grid_hidden_by_pcolor = self.get_axisbelow() is True
+        if grid_active and not grid_hidden_by_pcolor:
             _api.warn_deprecated(
                 "3.5", message="Auto-removal of grids by pcolor() and "
                 "pcolormesh() is deprecated since %(since)s and will be "
