ORL: Fix tuple error when removed every instance

Author: matthewsedam

adlib/learners/outlier_removal_learner.py

@@ -50,7 +50,17 @@ def train(self):
         iteration = 0
 
         while cutoff < max_cutoff:
-            fvs, labels = self._remove_outliers(fvs, labels, cutoff)
+            try:
+                fvs, labels = self._remove_outliers(fvs, labels, cutoff)
+            except:  # Failure - usually when there are no instances left (removes all)
+                if self.verbose:
+                    print('\nORL Iteration:', iteration, '- factor:', factor,
+                          '- cutoff:', cutoff, '- FAILURE\n')
+
+                factor += 1
+                cutoff = base_cutoff * factor
+                fvs, labels = deepcopy(orig_fvs), deepcopy(orig_labels)
+                iteration += 1
 
             self.w = np.full(fvs.shape[1], 0.0)
             for i, fv in enumerate(fvs):
@@ -97,7 +107,7 @@ def _remove_outliers(self, fvs, labels, cutoff):
         while old_number_of_instances != len(labels):
             # Assume at least 50% are non-poisonous instances
             if iteration > 0 and old_number_of_instances < 0.5 * original_num_instances:
-                break
+                raise ValueError()
 
             if self.verbose:
                 print('Iteration:', iteration, '- num_instances:', len(labels))