Added doc to store_leaf_values

Signed-off-by: Adam Li <adam2392@gmail.com>

Author: adam2392

sklearn/ensemble/_forest.py

@@ -822,6 +822,11 @@ def get_leaf_node_samples(self, X):
             samples, since the number of samples that fall in a leaf node is
             variable. Each array-like has shape (n_leaf_node_samples, n_outputs).
         """
+        if not self.store_leaf_values:
+            raise RuntimeError(
+                "Leaf node samples are not available when store_leaf_values=False"
+            )
+
         check_is_fitted(self)
         # Check data
         X = self._validate_X_predict(X)
@@ -1520,6 +1525,9 @@ class RandomForestClassifier(ForestClassifier):
 
         .. versionadded:: 0.22
 
+    store_leaf_values : bool, default=False
+        Whether to store the leaf values in the ``get_leaf_node_samples`` function.
+
     Attributes
     ----------
     estimator_ : :class:`~sklearn.tree.DecisionTreeClassifier`
@@ -1879,6 +1887,9 @@ class RandomForestRegressor(ForestRegressor):
 
         .. versionadded:: 0.22
 
+    store_leaf_values : bool, default=False
+        Whether to store the leaf values in the ``get_leaf_node_samples`` function.
+
     Attributes
     ----------
     estimator_ : :class:`~sklearn.tree.DecisionTreeRegressor`
@@ -2232,6 +2243,9 @@ class ExtraTreesClassifier(ForestClassifier):
 
         .. versionadded:: 0.22
 
+    store_leaf_values : bool, default=False
+        Whether to store the leaf values in the ``get_leaf_node_samples`` function.
+
     Attributes
     ----------
     estimator_ : :class:`~sklearn.tree.ExtraTreesClassifier`
@@ -2576,6 +2590,9 @@ class ExtraTreesRegressor(ForestRegressor):
 
         .. versionadded:: 0.22
 
+    store_leaf_values : bool, default=False
+        Whether to store the leaf values in the ``get_leaf_node_samples`` function.
+
     Attributes
     ----------
     estimator_ : :class:`~sklearn.tree.ExtraTreeRegressor`