Fixed bug where empty RoiSet throws error when calling classify_by

model_server/base/roiset.py

@@ -486,6 +486,9 @@ class RoiSet(object):
         :param object_classification_model: InstanceSegmentation model object
         :return: None
         """
+        if self.count == 0:
+            self._df['classify_by_' + name] = None
+            return True
 
         input_acc = self.get_patches_acc(channels=channels, expanded=False, pad_to=None)  # all channels
 

tests/base/test_roiset.py

@@ -81,6 +81,8 @@ class TestRoiSetMonoProducts(BaseTestRoiSetMonoProducts, unittest.TestCase):
         zero_obmap = InMemoryDataAccessor(np.zeros(self.seg_mask.shape, self.seg_mask.dtype))
         roiset = RoiSet.from_object_ids(self.stack_ch_pa, zero_obmap)
         self.assertEqual(roiset.count, 0)
+        roiset.classify_by('dummy_class', [0], DummyInstanceSegmentationModel())
+        self.assertTrue('classify_by_dummy_class' in roiset.get_df().columns)
 
     def test_slices_are_valid(self):
         roiset = self._make_roi_set()