84 lines
3.3 KiB
Python
84 lines
3.3 KiB
Python
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# Copyright 2022 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""Utility to manipulate resource variables."""
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from tensorflow.python.framework import composite_tensor
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from tensorflow.python.framework import ops
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from tensorflow.python.util import _pywrap_utils
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from tensorflow.python.util import nest
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def convert_variables_to_tensors(values):
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"""Converts `ResourceVariable`s in `values` to `Tensor`s.
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If an object is a `CompositeTensor` and overrides its
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`_convert_variables_to_tensors` method, its `ResourceVariable` components
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will also be converted to `Tensor`s. Objects other than `ResourceVariable`s
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in `values` will be returned unchanged.
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Args:
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values: A nested structure of `ResourceVariable`s, or any other objects.
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Returns:
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A new structure with `ResourceVariable`s in `values` converted to `Tensor`s.
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"""
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def _convert_resource_variable_to_tensor(x):
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if _pywrap_utils.IsResourceVariable(x):
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return ops.convert_to_tensor(x)
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elif isinstance(x, composite_tensor.CompositeTensor):
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return composite_tensor.convert_variables_to_tensors(x)
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else:
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return x
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return nest.map_structure(_convert_resource_variable_to_tensor, values)
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def replace_variables_with_atoms(values):
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"""Replaces `ResourceVariable`s in `values` with tf.nest atoms.
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This function is mostly for backward compatibility. Historically,
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`ResourceVariable`s are treated as tf.nest atoms. This is no
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longer the case after `ResourceVariable` becoming `CompositeTensor`.
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Unfortunately, tf.nest doesn't allow customization of what objects
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are treated as atoms. Calling this function to manually convert
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`ResourceVariable`s to atoms to avoid breaking tf.assert_same_structure
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with inputs of a `ResourceVariable` and an atom, like a `Tensor`.
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The specific implementation uses 0 as the tf.nest atom, but other tf.nest
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atoms could also serve the purpose. Note, the `TypeSpec` of None is not a
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tf.nest atom.
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Objects other than `ResourceVariable`s in `values` will be returned unchanged.
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Note: this function does not look into `CompositeTensor`s. Replacing
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`ResourceVariable`s in a `CompositeTensor` with atoms will change the
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`TypeSpec` of the `CompositeTensor`, which violates the semantics of
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`CompositeTensor` and tf.nest. So `ResourceVariable`s in `CompositeTensor`s
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will be returned as they are.
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Args:
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values: A nested structure of `ResourceVariable`s, or any other objects.
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Returns:
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A new structure with `ResourceVariable`s in `values` converted to atoms.
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"""
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def _replace_resource_variable_with_atom(x):
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if _pywrap_utils.IsResourceVariable(x):
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return 0 # tf.nest treats 0 or tf.constant(0) as an atom.
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else:
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return x
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return nest.map_structure(_replace_resource_variable_with_atom, values)
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