def transform(self, fn, dtype=None, *args, **kwargs):
rdd = self._rdd.map(fn)<EOL>if dtype is None:<EOL><INDENT>return self.__class__(rdd, noblock=True, **self.get_params())<EOL><DEDENT>if dtype is np.ndarray:<EOL><INDENT>return ArrayRDD(rdd, bsize=self.bsize, noblock=True)<EOL><DEDENT>elif dtype is sp.spmatrix:<EOL><INDENT>return SparseRDD(rdd, bsize=self.bsize, noblock=True)<EOL><DEDENT>else:<EOL><INDENT>return BlockRDD(rdd, bsize=self.bsize, dtype=dtype, noblock=True)<EOL><DEDENT>
Equivalent to map, compatibility purpose only.
        Column parameter ignored.