implement SklearnClassifier.batch_prob_classify

And remove SklearnClassifier.classify; already inherited from
ClassifierI.

nltk/classify/scikitlearn.py

@@ -1,4 +1,5 @@
 from nltk.classify.api import ClassifierI
+from nltk.probability import DictionaryProbDist
 
 import numpy as np
 
@@ -25,8 +26,10 @@ def batch_classify(self, featuresets):
         y = self._clf.predict(X)
         return [self._index_label[int(yi)] for yi in y]
 
-    def classify(self, featureset):
-        return self.batch_classify([featureset])
+    def batch_prob_classify(self, featuresets):
+        X = self._featuresets_to_array(featuresets)
+        y_proba = self._clf.predict_proba(X)
+        return [self._make_probdist(y_proba[i]) for i in xrange(len(y_proba))]
 
     def labels(self):
         return self._label_index.keys()
@@ -72,6 +75,10 @@ def _featuresets_to_array(self, featuresets):
 
         return X
 
+    def _make_probdist(self, y_proba):
+        return DictionaryProbDist(dict((self._index_label[i], p)
+                                       for i, p in enumerate(y_proba)))
+
 
 if __name__ == "__main__":
     from nltk.classify.util import names_demo, binary_names_demo_features