fix str label issue in ensemblevoteclassifier with refit=false

docs/sources/CHANGELOG.md

@@ -26,7 +26,7 @@ The CHANGELOG for the current development version is available at
 
 ##### Bug Fixes
 
-- -
+- Fixed issue when class labels were provided to the `EnsembleVoteClassifier` when `refit` was set to `false`. ([#322](https://github.com/rasbt/mlxtend/issues/322))
 
 
 

mlxtend/classifier/ensemble_vote.py

@@ -260,7 +260,12 @@ def get_params(self, deep=True):
 
     def _predict(self, X):
         """Collect results from clf.predict calls."""
-        return np.asarray([clf.predict(X) for clf in self.clfs_]).T
+
+        if self.refit:
+            return np.asarray([clf.predict(X) for clf in self.clfs_]).T
+        else:
+            return np.asarray([self.le_.transform(clf.predict(X))
+                               for clf in self.clfs_]).T
 
     def _predict_probas(self, X):
         """Collect results from clf.predict_proba calls."""

mlxtend/classifier/tests/test_ensemble_vote_classifier.py

@@ -164,3 +164,34 @@ def test_string_labels_python_list():
                              scoring='accuracy')
     scores_mean = (round(scores.mean(), 2))
     assert(scores_mean == 0.94)
+
+
+def test_string_labels_refit_false():
+    np.random.seed(123)
+    clf1 = LogisticRegression()
+    clf2 = RandomForestClassifier()
+    clf3 = GaussianNB()
+
+    y_str = y.copy()
+    y_str = y_str.astype(str)
+    y_str[:50] = 'a'
+    y_str[50:100] = 'b'
+    y_str[100:150] = 'c'
+
+    clf1.fit(X, y_str)
+    clf2.fit(X, y_str)
+    clf3.fit(X, y_str)
+
+    eclf = EnsembleVoteClassifier(clfs=[clf1, clf2, clf3],
+                                  voting='hard',
+                                  refit=False)
+
+    eclf.fit(X, y_str)
+    assert round(eclf.score(X, y_str), 2) == 0.97
+
+    eclf = EnsembleVoteClassifier(clfs=[clf1, clf2, clf3],
+                                  voting='soft',
+                                  refit=False)
+
+    eclf.fit(X, y_str)
+    assert round(eclf.score(X, y_str), 2) == 0.97