DOC add example to tree.ExtraTreeClassifier (scikit-learn#16671)

nilichen · Jonathan Rahn · Katrina Ni · web-flow · commit f7fd231ab48f · 2020-03-11T20:07:12.000+01:00
Co-authored-by: Jonathan Rahn &lt;jonathan.rahn@42digital.de&gt;
Co-authored-by: Katrina Ni &lt;kani@tableau.com&gt;
diff --git a/sklearn/tree/_classes.py b/sklearn/tree/_classes.py
@@ -1477,6 +1477,21 @@ class ExtraTreeClassifier(DecisionTreeClassifier):
 
     .. [1] P. Geurts, D. Ernst., and L. Wehenkel, "Extremely randomized trees",
            Machine Learning, 63(1), 3-42, 2006.
+
+    Examples
+    --------
+    >>> from sklearn.datasets import load_iris
+    >>> from sklearn.model_selection import train_test_split
+    >>> from sklearn.ensemble import BaggingClassifier
+    >>> from sklearn.tree import ExtraTreeClassifier
+    >>> X, y = load_iris(return_X_y=True)
+    >>> X_train, X_test, y_train, y_test = train_test_split(
+    ...    X, y, random_state=0)
+    >>> extra_tree = ExtraTreeClassifier(random_state=0)
+    >>> cls = BaggingClassifier(extra_tree, random_state=0).fit(
+    ...    X_train, y_train)
+    >>> cls.score(X_test, y_test)
+    0.8947...
     """
     def __init__(self,
                  criterion="gini",
