def extra_reading_spec(self):
    """Additional data fields to store on disk and their decoders."""
    data_fields = {
        "frame_number": tf.FixedLenFeature([1], tf.int64),
        "action": tf.FixedLenFeature([4], tf.float32),
    }
    decoders = {
        "frame_number":
            contrib.slim().tfexample_decoder.Tensor(tensor_key="frame_number"),
        "action":
            contrib.slim().tfexample_decoder.Tensor(tensor_key="action"),
    }
    return data_fields, decoders
Additional data fields to store on disk and their decoders.
tensor2tensor/data_generators/bair_robot_pushing.py