[FIX] Manifold Learning: handling out of memory error

Orange/widgets/unsupervised/owmanifoldlearning.py

@@ -188,6 +188,7 @@ class Error(OWWidget.Error):
         sparse_methods = Msg('Only t-SNE method supported on sparse data')
         sparse_tsne_distance = Msg('Chebyshev, Jaccard, and Mahalanobis '
                                    'distances not supported with sparse data.')
+        out_of_memory = Msg("Out of memory")
 
     def __init__(self):
         self.data = None
@@ -271,6 +272,8 @@ def apply(self):
                     self.Error.n_neighbors_too_small("{}".format(n))
                 else:
                     self.Error.manifold_error(e.args[0])
+            except MemoryError:
+                self.Error.out_of_memory()
             except np.linalg.linalg.LinAlgError as e:
                 self.Error.manifold_error(str(e))
         self.Outputs.transformed_data.send(out)

Orange/widgets/unsupervised/tests/test_owmanifoldlearning.py

@@ -1,5 +1,7 @@
 # Test methods with long descriptive names can omit docstrings
 # pylint: disable=missing-docstring
+from unittest.mock import patch, Mock
+
 import numpy as np
 from scipy import sparse
 
@@ -108,3 +110,16 @@ def test_singular_matrices(self):
         self.assertFalse(self.widget.Error.manifold_error.is_shown())
         self.widget.apply_button.button.click()
         self.assertTrue(self.widget.Error.manifold_error.is_shown())
+
+    def test_out_of_memory(self):
+        """
+        Show error message when out of memory.
+        GH-2441
+        """
+        table = Table("iris")
+        with patch("Orange.projection.manifold.MDS.__call__", Mock()) as mock:
+            mock.side_effect = MemoryError
+            self.send_signal("Data", table)
+            self.widget.manifold_methods_combo.activated.emit(1)
+            self.widget.apply_button.button.click()
+            self.assertTrue(self.widget.Error.out_of_memory.is_shown())