'Array mapping from feature integer indices to feature name'

def get_feature_names(self):

    if ((not hasattr(self, 'vocabulary_')) or (len(self.vocabulary_) == 0)):
        raise ValueError("Vocabulary    wasn't    fitted    or    is    empty!")
    return [t for (t, i) in sorted(iter(self.vocabulary_.items()), key=itemgetter(1))]
