return one dict which contains "data" and "label"

def next(self):
        """return one dict which contains "data" and "label" """
        if self.iter_next():
            self.data, self.label = self._read()
            return {self.data_name  :  self.data[0][1],
                    self.label_name :  self.label[0][1]}
        else:
            raise StopIteration