1# Copyright 2020 The TensorFlow Authors. All Rights Reserved.
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14# ==============================================================================
15"""Ops for compressing and uncompressing dataset elements."""
16from __future__ import absolute_import
17from __future__ import division
18from __future__ import print_function
19
20from tensorflow.python.data.util import structure
21from tensorflow.python.ops import gen_experimental_dataset_ops as ged_ops
22
23
24def compress(element):
25  """Compress a dataset element.
26
27  Args:
28    element: A nested structure of types supported by Tensorflow.
29
30  Returns:
31    A variant tensor representing the compressed element. This variant can be
32    passed to `uncompress` to get back the original element.
33  """
34  element_spec = structure.type_spec_from_value(element)
35  tensor_list = structure.to_tensor_list(element_spec, element)
36  return ged_ops.compress_element(tensor_list)
37
38
39def uncompress(element, output_spec):
40  """Uncompress a compressed dataset element.
41
42  Args:
43    element: A scalar variant tensor to uncompress. The element should have been
44      created by calling `compress`.
45    output_spec: A nested structure of `tf.TypeSpec` representing the type(s) of
46      the uncompressed element.
47
48  Returns:
49    The uncompressed element.
50  """
51  flat_types = structure.get_flat_tensor_types(output_spec)
52  flat_shapes = structure.get_flat_tensor_shapes(output_spec)
53  tensor_list = ged_ops.uncompress_element(
54      element, output_types=flat_types, output_shapes=flat_shapes)
55  return structure.from_tensor_list(output_spec, tensor_list)
56