Merge 48d3c7e into cb01400

sklearn/compose/tests/test_column_transformer.py

@@ -777,3 +777,8 @@ def test_column_transformer_no_estimators():
     assert len(ct.transformers_) == 1
     assert ct.transformers_[-1][0] == 'remainder'
     assert ct.transformers_[-1][2] == [0, 1, 2]
+
+
+def test_column_transformer_no_estimators_set_params():
+    ct = ColumnTransformer([]).set_params(n_jobs=2)
+    assert ct.n_jobs == 2

sklearn/utils/metaestimators.py

@@ -41,7 +41,10 @@ def _set_params(self, attr, **params):
         if attr in params:
             setattr(self, attr, params.pop(attr))
         # 2. Step replacement
-        names, _ = zip(*getattr(self, attr))
+        items = getattr(self, attr)
+        names = []
+        if items:
+            names, _ = zip(*items)
         for name in list(six.iterkeys(params)):
             if '__' not in name and name in names:
                 self._replace_estimator(attr, name, params.pop(name))