def predictNew(clf, sentences, groups):
    """
    Use trained classifier to make predictions on new samples

    :param clf:             trained classifier (clould be loaded from the model file)
    :param sentences:       a list of new comments (must in the form of list)
    :param groups:          dictionary from commment categories to indexes e.g. {'positive': 0, 'negative': 1, 'neutral': 2, 'question': 3}
    """
    groups = dict((y,x) for x,y in groups.iteritems())
    predicted = clf.predict(sentences)
    group_predict = [groups[i] for i in predicted]
   
    return group_predict