[FIX] Test Learners: Fix AUC for selected single target class

Orange/widgets/evaluate/owtestlearners.py

@@ -709,11 +709,41 @@ def results_merge(results):
 
 
 def results_one_vs_rest(results, pos_index):
+    from Orange.preprocess.transformation import Indicator
     actual = results.actual == pos_index
     predicted = results.predicted == pos_index
-    return Orange.evaluation.Results(
-        nmethods=1, domain=results.domain,
-        actual=actual, predicted=predicted)
+    if results.probabilities is not None:
+        c = results.probabilities.shape[2]
+        assert c >= 2
+        neg_indices = [i for i in range(c) if i != pos_index]
+        pos_prob = results.probabilities[:, :, [pos_index]]
+        neg_prob = np.sum(results.probabilities[:, :, neg_indices],
+                          axis=2, keepdims=True)
+        probabilities = np.dstack((neg_prob, pos_prob))
+    else:
+        probabilities = None
+
+    res = Orange.evaluation.Results()
+    res.actual = actual
+    res.predicted = predicted
+    res.folds = results.folds
+    res.row_indices = results.row_indices
+    res.probabilities = probabilities
+
+    value = results.domain.class_var.values[pos_index]
+    class_var = Orange.data.DiscreteVariable(
+        "I({}=={})".format(results.domain.class_var.name, value),
+        values=["False", "True"],
+        compute_value=Indicator(results.domain.class_var, pos_index)
+    )
+    domain = Orange.data.Domain(
+        results.domain.attributes,
+        [class_var],
+        results.domain.metas
+    )
+    res.data = None
+    res.domain = domain
+    return res
 
 
 def main(argv=None):

Orange/widgets/evaluate/tests/test_owtestlearners.py

@@ -0,0 +1,67 @@
+# pylint: disable=missing-docstring
+import numpy as np
+
+import unittest
+
+from Orange.data import Table
+from Orange.classification import MajorityLearner
+from Orange.regression import MeanLearner
+
+from Orange.evaluation import Results, TestOnTestData
+from Orange.widgets.tests.base import WidgetTest
+from Orange.widgets.evaluate.owtestlearners import OWTestLearners
+from Orange.widgets.evaluate import owtestlearners
+
+
+class TestOWTestLearners(WidgetTest):
+    def setUp(self):
+        super().setUp()
+        self.widget = self.create_widget(OWTestLearners)  # type: OWTestLearners
+
+    def test_basic(self):
+        data = Table("iris")[::3]
+        self.send_signal("Data", data)
+        self.send_signal("Learner", MajorityLearner(), 0)
+        res = self.get_output("Evaluation Results")
+        self.assertIsInstance(res, Results)
+        self.assertIsNotNone(res.domain)
+        self.assertIsNotNone(res.data)
+        self.assertIsNotNone(res.probabilities)
+
+        self.send_signal("Learner", None, 0)
+
+        data = Table("housing")[::10]
+        self.send_signal("Data", data)
+        self.send_signal("Learner", MeanLearner(), 0)
+        res = self.get_output("Evaluation Results")
+        self.assertIsInstance(res, Results)
+        self.assertIsNotNone(res.domain)
+        self.assertIsNotNone(res.data)
+
+
+class TestHelpers(unittest.TestCase):
+    def test_results_one_vs_rest(self):
+        data = Table("lenses")
+        learners = [MajorityLearner()]
+        res = TestOnTestData(data[1::2], data[::2], learners=learners)
+        r1 = owtestlearners.results_one_vs_rest(res, pos_index=0)
+        r2 = owtestlearners.results_one_vs_rest(res, pos_index=1)
+        r3 = owtestlearners.results_one_vs_rest(res, pos_index=2)
+
+        np.testing.assert_almost_equal(np.sum(r1.probabilities, axis=2), 1.0)
+        np.testing.assert_almost_equal(np.sum(r2.probabilities, axis=2), 1.0)
+        np.testing.assert_almost_equal(np.sum(r3.probabilities, axis=2), 1.0)
+
+        np.testing.assert_almost_equal(
+            r1.probabilities[:, :, 1] +
+            r2.probabilities[:, :, 1] +
+            r3.probabilities[:, :, 1],
+            1.0
+        )
+        self.assertEqual(r1.folds, res.folds)
+        self.assertEqual(r2.folds, res.folds)
+        self.assertEqual(r3.folds, res.folds)
+
+        np.testing.assert_equal(r1.row_indices, res.row_indices)
+        np.testing.assert_equal(r2.row_indices, res.row_indices)
+        np.testing.assert_equal(r3.row_indices, res.row_indices)