rake.py 文件源码

def _generate_phrases(self, sentences):
        """Method to generate contender phrases given the sentences of the text
        document.

        :param sentences: List of strings where each string represents a
                          sentence which forms the text.
        :return: Set of string tuples where each tuple is a collection
                 of words forming a contender phrase.
        """
        phrase_list = set()
        # Create contender phrases from sentences.
        for sentence in sentences:
            word_list = [word.lower() for word in wordpunct_tokenize(sentence)]
            phrase_list.update(self._get_phrase_list_from_words(word_list))
        return phrase_list