Resolve "(LearnerND) add iso-surface plot feature"

Closes #112 (closed)

adaptive/learner/learnerND.py

@@ -678,7 +678,7 @@ class LearnerND(BaseLearner):
             # If the volume of the two triangles combined is zero then they
             # belong to the same plane.
             for simplex_key, color in color_dict.items():
-                points = np.array([hull.points[i] for i in np.unique(simplex_key + simplex)])
+                points = np.array([hull.points[i] for i in set(simplex_key + simplex)])
                 if np.linalg.matrix_rank(points[1:] - points[0]) < 3:
                     return color
                 if scipy.spatial.ConvexHull(points).volume < 1e-5:
@@ -691,4 +691,4 @@ class LearnerND(BaseLearner):
         x, y, z = zip(*self._bounds_points)
         i, j, k = hull.simplices.T
         return plotly.graph_objs.Mesh3d(x=x, y=y, z=z, i=i, j=j, k=k,
-                                        facecolor=(colors), opacity=opacity)
+                                        facecolor=colors, opacity=opacity)