Contingency.Discrete: Fix deepcopy and pickle

Orange/statistics/contingency.py

@@ -179,9 +179,20 @@ def __reduce__(self):
         return (
             _create_discrete,
             (Discrete, np.copy(self), self.col_variable, self.row_variable,
-             self.col_unknowns, self.row_unknowns)
+             self.col_unknowns, self.row_unknowns, self.unknowns)
         )
 
+    def __array_finalize__(self, obj):
+        # defined in __new__, pylint: disable=attribute-defined-outside-init
+        """See http://docs.scipy.org/doc/numpy/user/basics.subclassing.html"""
+        if obj is None:
+            return
+        self.col_variable = getattr(obj, 'col_variable', None)
+        self.row_variable = getattr(obj, 'row_variable', None)
+        self.col_unknowns = getattr(obj, 'col_unknowns', None)
+        self.row_unknowns = getattr(obj, 'row_unknowns', None)
+        self.unknowns = getattr(obj, 'unknowns', None)
+
 
 class Continuous:
     def __init__(self, dat, col_variable=None, row_variable=None,

Orange/tests/test_contingency.py

@@ -1,6 +1,6 @@
 # Test methods with long descriptive names can omit docstrings
 # pylint: disable=missing-docstring
-
+import copy
 import unittest
 from unittest.mock import Mock
 
@@ -71,6 +71,13 @@ def test_discrete_missing(self):
         np.testing.assert_almost_equal(cont.row_unknowns, [0, 0])
         self.assertEqual(1, cont.unknowns)
 
+    def test_deepcopy(self):
+        cont = contingency.Discrete(self.zoo, 0)
+        dc = copy.deepcopy(cont)
+        self.assertEqual(dc, cont)
+        self.assertEqual(dc.col_variable, cont.col_variable)
+        self.assertEqual(dc.row_variable, cont.row_variable)
+
     def test_array_with_unknowns(self):
         d = data.Table("zoo")
         d.Y[2] = float("nan")