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Python

# Copyright 2015 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Gradients for operators defined in data_flow_ops.py."""
from tensorflow.python.framework import dtypes
from tensorflow.python.framework import indexed_slices
from tensorflow.python.framework import ops
from tensorflow.python.ops import array_ops
from tensorflow.python.ops import data_flow_ops
from tensorflow.python.ops import math_ops
@ops.RegisterGradient("DynamicPartition")
def _DynamicPartitionGrads(op, *grads):
"""Gradients for DynamicPartition."""
data = op.inputs[0]
indices = op.inputs[1]
num_partitions = op.get_attr("num_partitions")
prefix_shape = array_ops.shape(indices)
original_indices = array_ops.reshape(
math_ops.range(math_ops.reduce_prod(prefix_shape)), prefix_shape)
partitioned_indices = data_flow_ops.dynamic_partition(
original_indices, indices, num_partitions)
reconstructed = data_flow_ops.parallel_dynamic_stitch(partitioned_indices,
grads)
reconstructed = array_ops.reshape(reconstructed, array_ops.shape(data))
return [reconstructed, None]
@ops.RegisterGradient("DynamicStitch")
@ops.RegisterGradient("ParallelDynamicStitch")
def _DynamicStitchGrads(op, grad):
"""Gradients for DynamicStitch and ParallelDynamicStitch."""
num_values = len(op.inputs) // 2
indices_grad = [None] * num_values
def AsInt32(x):
return (x if op.inputs[0].dtype == dtypes.int32 else
math_ops.cast(x, dtypes.int32))
inputs = [AsInt32(op.inputs[i]) for i in range(num_values)]
if isinstance(grad, indexed_slices.IndexedSlices):
output_shape = array_ops.shape(op.outputs[0])
output_rows = output_shape[0]
grad = math_ops.unsorted_segment_sum(grad.values, grad.indices, output_rows)
ids = []
current_size = array_ops.zeros([], dtype=dtypes.int32)
for inp in inputs:
num_elements = math_ops.cast(array_ops.size(inp), current_size.dtype)
flat_id = math_ops.range(current_size, current_size + num_elements)
ids.append(array_ops.reshape(flat_id, array_ops.shape(inp)))
current_size += num_elements
stitch_op = (
data_flow_ops.parallel_dynamic_stitch
if op.type == "ParallelDynamicStitch"
else data_flow_ops.dynamic_stitch
)
stitched_ids = stitch_op(inputs, ids)
values_grad = []
num_inner_dims = array_ops.rank(grad) - 1
for inp, single_id in zip(inputs, ids):
value_grad = array_ops.gather(grad, inp)
winning_ids = array_ops.gather(stitched_ids, inp)
is_winner = math_ops.equal(winning_ids, single_id)
mask = math_ops.cast(is_winner, value_grad.dtype)
winner_shape = array_ops.shape(is_winner)
mask_shape = array_ops.concat(
[
winner_shape,
array_ops.ones([num_inner_dims], dtype=winner_shape.dtype),
],
axis=0,
)
values_grad.append(value_grad * array_ops.reshape(mask, mask_shape))
return indices_grad + values_grad
ops.NotDifferentiable("Queue")
ops.NotDifferentiable("QueueEnqueue")
ops.NotDifferentiable("QueueEnqueueMany")
ops.NotDifferentiable("QueueDequeue")
ops.NotDifferentiable("QueueDequeueMany")
ops.NotDifferentiable("QueueDequeueUpTo")
ops.NotDifferentiable("QueueClose")
ops.NotDifferentiable("QueueSize")
ops.NotDifferentiable("Stack")
ops.NotDifferentiable("StackPush")
ops.NotDifferentiable("StackPop")
ops.NotDifferentiable("StackClose")
ops.NotDifferentiable("GetSessionHandle")
ops.NotDifferentiable("GetSessionHandleV2")
ops.NotDifferentiable("GetSessionTensor")
ops.NotDifferentiable("DeleteSessionTensor")