[MRG+1] FIX Add missing mixins to ClassifierChain (scikit-learn#9473)

jnothman · AishwaryaRK · commit 515faddb156f · 2017-08-29T09:58:55.000+05:30
* Add missing mixins to ClassifierChain

* Fix import in test
diff --git a/sklearn/multioutput.py b/sklearn/multioutput.py
@@ -368,7 +368,7 @@ def score(self, X, y):
         return np.mean(np.all(y == y_pred, axis=1))
 
 
-class ClassifierChain(BaseEstimator):
+class ClassifierChain(BaseEstimator, ClassifierMixin, MetaEstimatorMixin):
     """A multi-label model that arranges binary classifiers into a chain.
 
     Each model makes a prediction in the order specified by the chain using
diff --git a/sklearn/tests/test_multioutput.py b/sklearn/tests/test_multioutput.py
@@ -29,6 +29,7 @@
 from sklearn.multioutput import MultiOutputClassifier
 from sklearn.multioutput import MultiOutputRegressor
 from sklearn.svm import LinearSVC
+from sklearn.base import ClassifierMixin
 from sklearn.utils import shuffle
 
 
@@ -380,6 +381,8 @@ def test_classifier_chain_fit_and_predict_with_logistic_regression():
     assert_equal([c.coef_.size for c in classifier_chain.estimators_],
                  list(range(X.shape[1], X.shape[1] + Y.shape[1])))
 
+    assert isinstance(classifier_chain, ClassifierMixin)
+
 
 def test_classifier_chain_fit_and_predict_with_linear_svc():
     # Fit classifier chain and verify predict performance using LinearSVC
