tf_rand_ops.py 文件源码

def random_crop(value, size, seed=None, name=None):
  """Randomly crops a tensor to a given size.

  Slices a shape `size` portion out of `value` at a uniformly chosen offset.
  Requires `value.shape >= size`.

  If a dimension should not be cropped, pass the full size of that dimension.
  For example, RGB images can be cropped with
  `size = [crop_height, crop_width, 3]`.

  Args:
    value: Input tensor to crop.
    size: 1-D tensor with size the rank of `value`.
    seed: Python integer. Used to create a random seed. See
      @{tf.set_random_seed}
      for behavior.
    name: A name for this operation (optional).

  Returns:
    A cropped tensor of the same rank as `value` and shape `size`.
  """
  # TODO(shlens): Implement edge case to guarantee output size dimensions.
  # If size > value.shape, zero pad the result so that it always has shape
  # exactly size.
  with ops.name_scope(name, "random_crop", [value, size]) as name:
    value = ops.convert_to_tensor(value, name="value")
    size = ops.convert_to_tensor(size, dtype=dtypes.int32, name="size")
    shape = array_ops.shape(value)
    check = control_flow_ops.Assert(
        math_ops.reduce_all(shape >= size),
        ["Need value.shape >= size, got ", shape, size],
        summarize=1000)
    shape = control_flow_ops.with_dependencies([check], shape)
    limit = shape - size + 1
    offset = random_uniform(
        array_ops.shape(shape),
        dtype=size.dtype,
        maxval=size.dtype.max,
        seed=seed) % limit
    return array_ops.slice(value, offset, size, name=name)