Merge pull request #3142 from robertcv/fixes/kmeans_error

OWKMeans: add error for data with no features

Orange/widgets/unsupervised/owkmeans.py

@@ -109,6 +109,7 @@ class Error(widget.OWWidget.Error):
         not_enough_data = widget.Msg(
             "Too few ({}) unique data instances for {} clusters"
         )
+        no_attributes = widget.Msg("Data is missing features.")
 
     class Warning(widget.OWWidget.Warning):
         no_silhouettes = widget.Msg(
@@ -255,6 +256,10 @@ def enough_data_instances(self, k):
         """k cannot be larger than the number of data instances."""
         return len(self.data) >= k
 
+    @property
+    def has_attributes(self):
+        return len(self.data.domain.attributes)
+
     @staticmethod
     def _compute_clustering(data, k, init, n_init, max_iter, silhouette, random_state):
         # type: (Table, int, str, int, int, bool) -> KMeansModel
@@ -391,12 +396,18 @@ def commit(self):
         # cause flickering when the clusters are computed quickly, so this is
         # the better alternative
         self.table_model.clear_scores()
-        self.mainArea.setVisible(self.optimize_k and self.data is not None)
+        self.mainArea.setVisible(self.optimize_k and self.data is not None and
+                                 self.has_attributes)
 
         if self.data is None:
             self.send_data()
             return
 
+        if not self.has_attributes:
+            self.Error.no_attributes()
+            self.send_data()
+            return
+
         if self.optimize_k:
             self.run_optimization()
         else:

Orange/widgets/unsupervised/tests/test_owkmeans.py

@@ -446,6 +446,13 @@ def assert_all_same(l):
         self.widget.smart_init = 1
         assert_all_same([cluster() for _ in range(5)])
 
+    def test_error_no_attributes(self):
+        domain = Domain([])
+        table = Table.from_domain(domain, n_rows=10)
+        self.widget.auto_commit = True
+        self.send_signal(self.widget.Inputs.data, table)
+        self.assertTrue(self.widget.Error.no_attributes.is_shown())
+
 
 if __name__ == "__main__":
     unittest.main()