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77 lines
2.3 KiB
77 lines
2.3 KiB
/* Copyright (c) 2016 Baidu, Inc. All Rights Reserve.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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#pragma once
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#include "Projection.h"
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namespace paddle {
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/**
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* @brief Context projection concatenate features in adjacent time steps in
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* a sequence. The i-th row of the output is the concatenation of
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* context_length rows of the input. The context_length rows are the
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* consecutive rows from the i+shift_start row.
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*
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* For example, assumed input (x) has 4 words and the dimension of each word
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* representation is 2. If we use zero to pad instead of learned weight to pad,
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* and the context_lenth is 3, the output (y) is:
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*
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* @code
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* x = [a1, a2;
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* b1, b2;
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* c1, c2;
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* d1, d2]
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* y = [0, 0, a1, a2, b1, b2;
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* a1, a2, b1, b2, c1, c2;
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* b1, b2, c1, c2, d1, d2;
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* c1, c2, d1, d2, 0, 0]
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* @endcode
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*
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* The config file api is context_projection.
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*/
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class ContextProjection : public Projection {
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public:
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/**
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* Constructor. If context_start is zero and context_lenth is one, it will
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* set trainable_padding false. trainable_padding is an optional arguments
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* and if it is set, constructor will set learned weight, which is used to
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* pad output.
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*/
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ContextProjection(const ProjectionConfig& config, ParameterPtr parameter,
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bool useGpu);
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virtual void forward();
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virtual void backward(const UpdateCallback& callback);
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virtual void resetState();
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virtual void setState(LayerStatePtr state);
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virtual LayerStatePtr getState();
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protected:
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std::unique_ptr<Weight> weight_;
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/// number of extra timesteps added at the beginning
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size_t beginPad_;
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/// number of extra timesteps added at the end
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size_t endPad_;
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/// state_ and state2_ are used in sequence generating and saved
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/// previous inputs.
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MatrixPtr state_;
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MatrixPtr state2_;
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};
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} // namespace paddle
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