Check features_names_in_ in sklearn.multioutput (#20847)

ogrisel · web-flow · commit 270ac2e1353c · 2021-08-26T16:50:21.000+02:00
diff --git a/sklearn/multioutput.py b/sklearn/multioutput.py
@@ -145,6 +145,8 @@ def partial_fit(self, X, y, classes=None, sample_weight=None):
 
         if first_time and hasattr(self.estimators_[0], "n_features_in_"):
             self.n_features_in_ = self.estimators_[0].n_features_in_
+        if first_time and hasattr(self.estimators_[0], "feature_names_in_"):
+            self.feature_names_in_ = self.estimators_[0].feature_names_in_
 
         return self
 
@@ -206,6 +208,8 @@ def fit(self, X, y, sample_weight=None, **fit_params):
 
         if hasattr(self.estimators_[0], "n_features_in_"):
             self.n_features_in_ = self.estimators_[0].n_features_in_
+        if hasattr(self.estimators_[0], "feature_names_in_"):
+            self.feature_names_in_ = self.estimators_[0].feature_names_in_
 
         return self
 
@@ -279,6 +283,12 @@ class MultiOutputRegressor(RegressorMixin, _MultiOutputEstimator):
 
         .. versionadded:: 0.24
 
+    feature_names_in_ : ndarray of shape (`n_features_in_`,)
+        Names of features seen during :term:`fit`. Only defined if the
+        underlying estimators expose such an attribute when fit.
+
+        .. versionadded:: 1.0
+
     Examples
     --------
     >>> import numpy as np
@@ -362,6 +372,12 @@ class MultiOutputClassifier(ClassifierMixin, _MultiOutputEstimator):
 
         .. versionadded:: 0.24
 
+    feature_names_in_ : ndarray of shape (`n_features_in_`,)
+        Names of features seen during :term:`fit`. Only defined if the
+        underlying estimators expose such an attribute when fit.
+
+        .. versionadded:: 1.0
+
     Examples
     --------
     >>> import numpy as np
@@ -675,6 +691,12 @@ class labels for each estimator in the chain.
 
         .. versionadded:: 0.24
 
+    feature_names_in_ : ndarray of shape (`n_features_in_`,)
+        Names of features seen during :term:`fit`. Defined only when `X`
+        has feature names that are all strings.
+
+        .. versionadded:: 1.0
+
     Examples
     --------
     >>> from sklearn.datasets import make_multilabel_classification
@@ -773,6 +795,7 @@ def decision_function(self, X):
             Returns the decision function of the sample for each model
             in the chain.
         """
+        X = self._validate_data(X, accept_sparse=True, reset=False)
         Y_decision_chain = np.zeros((X.shape[0], len(self.estimators_)))
         Y_pred_chain = np.zeros((X.shape[0], len(self.estimators_)))
         for chain_idx, estimator in enumerate(self.estimators_):
@@ -860,6 +883,12 @@ class RegressorChain(MetaEstimatorMixin, RegressorMixin, _BaseChain):
 
         .. versionadded:: 0.24
 
+    feature_names_in_ : ndarray of shape (`n_features_in_`,)
+        Names of features seen during :term:`fit`. Defined only when `X`
+        has feature names that are all strings.
+
+        .. versionadded:: 1.0
+
     Examples
     --------
     >>> from sklearn.multioutput import RegressorChain
diff --git a/sklearn/tests/test_common.py b/sklearn/tests/test_common.py
@@ -328,7 +328,6 @@ def test_check_n_features_in_after_fitting(estimator):
     "feature_extraction",
     "kernel_approximation",
     "model_selection",
-    "multioutput",
 }
 
 _estimators_to_test = list(

Original file line number	Diff line number	Diff line change
`@@ -328,7 +328,6 @@ def test_check_n_features_in_after_fitting(estimator):`
`328`	`328`	`"feature_extraction",`
`329`	`329`	`"kernel_approximation",`
`330`	`330`	`"model_selection",`
`331`		`- "multioutput",`
`332`	`331`	`}`
`333`	`332`
`334`	`333`	`_estimators_to_test = list(`