Add handling of special cases opacity

Author: Timoté Vaucher

packages/python/plotly/plotly/express/_core.py

@@ -1278,7 +1278,9 @@ def infer_config(args, constructor, trace_patch):
         if args["opacity"] is None:
             if "barmode" in args and args["barmode"] == "overlay":
                 trace_patch["marker"] = dict(opacity=0.5)
-        elif constructor != go.Densitymapbox:
+        elif constructor in [go.Densitymapbox, go.Pie, go.Funnel, go.Funnelarea]:
+            trace_patch["opacity"] = args["opacity"]
+        else:
             trace_patch["marker"] = dict(opacity=args["opacity"])
     if "line_group" in args:
         trace_patch["mode"] = "lines" + ("+markers+text" if args["text"] else "")