shape_utils.py 文件源码

def pad_tensor(t, length):
  """Pads the input tensor with 0s along the first dimension up to the length.

  Args:
    t: the input tensor, assuming the rank is at least 1.
    length: a tensor of shape [1]  or an integer, indicating the first dimension
      of the input tensor t after padding, assuming length <= t.shape[0].

  Returns:
    padded_t: the padded tensor, whose first dimension is length. If the length
      is an integer, the first dimension of padded_t is set to length
      statically.
  """
  t_rank = tf.rank(t)
  t_shape = tf.shape(t)
  t_d0 = t_shape[0]
  pad_d0 = tf.expand_dims(length - t_d0, 0)
  pad_shape = tf.cond(
      tf.greater(t_rank, 1), lambda: tf.concat([pad_d0, t_shape[1:]], 0),
      lambda: tf.expand_dims(length - t_d0, 0))
  padded_t = tf.concat([t, tf.zeros(pad_shape, dtype=t.dtype)], 0)
  if not _is_tensor(length):
    padded_t = _set_dim_0(padded_t, length)
  return padded_t