def pad_dataset_to_length(dataset, training, len_map=None):
  """Pad features less than specified length to specified length."""
  del training
  if len_map is None:
    return dataset

  def pad_to_len(x):
    for key, max_len in len_map.items():
      x_shape = tf.shape(x[key])
      x_len = x_shape[0]
      if x_len < max_len:
        pad_shape = [
            max_len - x_len,
        ]
        zeros = tf.zeros(pad_shape, dtype=x[key].dtype)
        x[key] = tf.concat([x[key], zeros], 0)
    return x

  return dataset.map(pad_to_len)
Pad features less than specified length to specified length.
trax/data/tf_inputs.py