Add additional check when auto vmin/vmax are None.

erykoff · erykoff · commit 3d2ffef00b2f · 2022-09-19T09:43:55.000-07:00
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -4944,6 +4944,8 @@ def reduce_C_function(C: array) -> float
         if norm is not None:
             if norm.vmin is None and norm.vmax is None:
                 norm.autoscale_None(accum)
+            norm.vmin = np.ma.masked if norm.vmin is None else norm.vmin
+            norm.vmax = np.ma.masked if norm.vmax is None else norm.vmax
 
         if bins is not None:
             if not np.iterable(bins):
