FIX default parameter value of min_samples_leaf in BalancedRandomForestClassifier (#711)

zerolfx · glemaitre · web-flow · commit 703cee11ecd9 · 2020-06-08T20:29:37.000+02:00
Co-authored-by: Guillaume Lemaitre &lt;g.lemaitre58@gmail.com&gt;
diff --git a/doc/whats_new/v0.7.rst b/doc/whats_new/v0.7.rst
@@ -5,3 +5,17 @@ Version 0.7.0 (under development)
 
 Changelog
 ---------
+
+Changed models
+..............
+
+The following models might give some different results due to changes:
+
+- :class:`imblearn.ensemble.BalancedRandomForestClassifier`
+
+Bug fixes
+.........
+
+- Change the default value `min_samples_leaf` to be consistent with
+  scikit-learn.
+  :pr:`711` by :user:`zerolfx <zerolfx>`.
diff --git a/imblearn/ensemble/_forest.py b/imblearn/ensemble/_forest.py
@@ -302,7 +302,7 @@ def __init__(
         criterion="gini",
         max_depth=None,
         min_samples_split=2,
-        min_samples_leaf=2,
+        min_samples_leaf=1,
         min_weight_fraction_leaf=0.0,
         max_features="auto",
         max_leaf_nodes=None,
diff --git a/imblearn/ensemble/tests/test_forest.py b/imblearn/ensemble/tests/test_forest.py
@@ -116,7 +116,8 @@ def test_balanced_random_forest_oob(imbalanced_dataset):
         X, y, random_state=42, stratify=y
     )
     est = BalancedRandomForestClassifier(
-        oob_score=True, random_state=0, n_estimators=1000
+        oob_score=True, random_state=0, n_estimators=1000,
+        min_samples_leaf=2,
     )
 
     est.fit(X_train, y_train)

Original file line number	Diff line number	Diff line change
`@@ -116,7 +116,8 @@ def test_balanced_random_forest_oob(imbalanced_dataset):`
`116`	`116`	`X, y, random_state=42, stratify=y`
`117`	`117`	`)`
`118`	`118`	`est = BalancedRandomForestClassifier(`
`119`		`- oob_score=True, random_state=0, n_estimators=1000`
	`119`	`+ oob_score=True, random_state=0, n_estimators=1000,`
	`120`	`+ min_samples_leaf=2,`
`120`	`121`	`)`
`121`	`122`
`122`	`123`	`est.fit(X_train, y_train)`