context.py 文件源码

def transform(self, dstreams, transformFunc):
        """
        Create a new DStream in which each RDD is generated by applying
        a function on RDDs of the DStreams. The order of the JavaRDDs in
        the transform function parameter will be the same as the order
        of corresponding DStreams in the list.
        """
        jdstreams = [d._jdstream for d in dstreams]
        # change the final serializer to sc.serializer
        func = TransformFunction(self._sc,
                                 lambda t, *rdds: transformFunc(rdds).map(lambda x: x),
                                 *[d._jrdd_deserializer for d in dstreams])
        jfunc = self._jvm.TransformFunction(func)
        jdstream = self._jssc.transform(jdstreams, jfunc)
        return DStream(jdstream, self, self._sc.serializer)