add _last_non_passthrough_estimator

amueller · amueller · commit bc9df430ba51 · 2019-09-25T17:18:21.000-04:00
diff --git a/sklearn/pipeline.py b/sklearn/pipeline.py
@@ -244,6 +244,15 @@ def _final_estimator(self):
         estimator = self.steps[-1][1]
         return 'passthrough' if estimator is None else estimator
 
+    @property
+    def _final_non_passthrough_estimator(self):
+        final_estimator = None
+        for name, est in reversed(self.steps):
+            if est not in [None, 'passthrough']:
+                final_estimator = est
+                break
+        return final_estimator
+
     def _log_message(self, step_idx):
         if not self.verbose:
             return None
diff --git a/sklearn/tests/test_pipeline.py b/sklearn/tests/test_pipeline.py
@@ -699,6 +699,7 @@ def make():
     assert_array_equal([[exp]], pipeline.fit_transform(X, y))
     assert_array_equal([exp], pipeline.fit(X).predict(X))
     assert_array_equal(X, pipeline.inverse_transform([[exp]]))
+    assert pipeline._final_non_passthrough_estimator is mult5
 
     pipeline = make()
     pipeline.set_params(last=passthrough)
@@ -707,6 +708,7 @@ def make():
     assert_array_equal([[exp]], pipeline.fit(X, y).transform(X))
     assert_array_equal([[exp]], pipeline.fit_transform(X, y))
     assert_array_equal(X, pipeline.inverse_transform([[exp]]))
+    assert pipeline._final_non_passthrough_estimator is mult3
     assert_raise_message(AttributeError,
                          "'str' object has no attribute 'predict'",
                          getattr, pipeline, 'predict')
