@@ -2,6 +2,7 @@

 import numpy as np

 from skopt import Optimizer

+from collections import OrderedDict

 from adaptive.learner.base_learner import BaseLearner

 from adaptive.notebook_integration import ensure_holoviews

@@ -25,19 +26,24 @@ class SKOptLearner(Optimizer, BaseLearner):

     def __init__(self, function, **kwargs):

         self.function = function

-        self.pending_points = set()

-        self.data = {}

+        self.pending_points = list()

+        self.data = OrderedDict()

         super().__init__(**kwargs)

     def tell(self, x, y, fit=True):

-        self.pending_points.discard(x)

-        self.data[x] = y

-        super().tell([x], y, fit)

+        if x in self.pending_points:

+            self.pending_points.remove(x)

+        if hasattr(x, '__iter__'):

+            self.data[tuple(x)] = y

+            super().tell(x, y, fit)

+        else:

+            self.data[x] = y

+            super().tell([x], y, fit)

     def tell_pending(self, x):

         # 'skopt.Optimizer' takes care of points we

         # have not got results for.

-        self.pending_points.add(x)

+        self.pending_points.append(x)

     def remove_unfinished(self):

         pass