Fix plot_contour for choice parameters (#69)

Summary:
These indices are flipped--the value we want is the actual parameter value, not the number of occurrences.

Fixes #68
Pull Request resolved: #69

Reviewed By: amurthy1

Differential Revision: D15192619

Pulled By: sdsingh

fbshipit-source-id: 28445e1f8e263e35151e1b20a140b59357c949de

ax/plot/helper.py

@@ -400,7 +400,7 @@ def get_fixed_values(
             if isinstance(parameter, FixedParameter):
                 setx[p_name] = parameter.value
             elif isinstance(parameter, ChoiceParameter):
-                setx[p_name] = Counter(vals).most_common(1)[0][1]
+                setx[p_name] = Counter(vals).most_common(1)[0][0]
             elif isinstance(parameter, RangeParameter):
                 setx[p_name] = parameter._cast(np.mean(vals))