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sequence_last.cc
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sequence_last.cc
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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
/*!
* Copyright (c) 2015 by Contributors
* \file sequence_last.cc
* \brief
* \author Sebastian Bodenstein
*/
#include "./sequence_last-inl.h"
namespace mxnet {
namespace op {
template <>
Operator *CreateOp<cpu>(SequenceLastParam param, int dtype, int itype) {
Operator *op = nullptr;
MSHADOW_TYPE_SWITCH(dtype, DType, {
MSHADOW_TYPE_SWITCH(itype, IType, {
op = new SequenceLastOp<cpu, DType, IType>(param);
});
});
return op;
}
// DO_BIND_DISPATCH comes from operator_common.h
Operator *SequenceLastProp::CreateOperatorEx(Context ctx,
mxnet::ShapeVector *in_shape,
std::vector<int> *in_type) const {
if (in_type->size() >= 2 && (*in_type)[1] != -1) {
DO_BIND_DISPATCH(CreateOp, param_, (*in_type)[0], (*in_type)[1]);
}
// sequence_length not passed in, so fall back to using int32/int64 dtype for second argument
// second argument is the dtype of the sequence_length NDArray
// use int32 or int64 as index dtype based on build flag
#if MXNET_USE_INT64_TENSOR_SIZE == 1
DO_BIND_DISPATCH(CreateOp, param_, (*in_type)[0], mshadow::kInt64);
#else
DO_BIND_DISPATCH(CreateOp, param_, (*in_type)[0], mshadow::kInt32);
#endif
}
DMLC_REGISTER_PARAMETER(SequenceLastParam);
MXNET_REGISTER_OP_PROPERTY(SequenceLast, SequenceLastProp)
.describe(R"code(Takes the last element of a sequence.
This function takes an n-dimensional input array of the form
[max_sequence_length, batch_size, other_feature_dims] and returns a (n-1)-dimensional array
of the form [batch_size, other_feature_dims].
Parameter `sequence_length` is used to handle variable-length sequences. `sequence_length` should be
an input array of positive ints of dimension [batch_size]. To use this parameter,
set `use_sequence_length` to `True`, otherwise each example in the batch is assumed
to have the max sequence length.
.. note:: Alternatively, you can also use `take` operator.
Example::
x = [[[ 1., 2., 3.],
[ 4., 5., 6.],
[ 7., 8., 9.]],
[[ 10., 11., 12.],
[ 13., 14., 15.],
[ 16., 17., 18.]],
[[ 19., 20., 21.],
[ 22., 23., 24.],
[ 25., 26., 27.]]]
// returns last sequence when sequence_length parameter is not used
SequenceLast(x) = [[ 19., 20., 21.],
[ 22., 23., 24.],
[ 25., 26., 27.]]
// sequence_length is used
SequenceLast(x, sequence_length=[1,1,1], use_sequence_length=True) =
[[ 1., 2., 3.],
[ 4., 5., 6.],
[ 7., 8., 9.]]
// sequence_length is used
SequenceLast(x, sequence_length=[1,2,3], use_sequence_length=True) =
[[ 1., 2., 3.],
[ 13., 14., 15.],
[ 25., 26., 27.]]
)code" ADD_FILELINE)
.add_argument("data", "NDArray-or-Symbol",
"n-dimensional input array of the form [max_sequence_length,"
" batch_size, other_feature_dims] where n>2")
.add_argument("sequence_length", "NDArray-or-Symbol",
"vector of sequence lengths of the form [batch_size]")
.add_arguments(SequenceLastParam::__FIELDS__());
} // namespace op
} // namespace mxnet