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128 lines
3.2 KiB
128 lines
3.2 KiB
/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved.
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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 <cstdint>
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#include <memory>
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#include <random>
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#include <vector>
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namespace paddle {
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namespace operators {
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namespace math {
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// TODO(wanghaoshuang): Support for GPU
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/**
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* Sample integers from [0, range).
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*/
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class Sampler {
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public:
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explicit Sampler(int64_t range, unsigned int seed = 0UL) : range_(range) {
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// PADDLE_ENFORCE_GT(range, 0, "Range should be greater than 0.");
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if (seed == 0) {
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std::random_device r;
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seed_ = r();
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} else {
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seed_ = seed;
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}
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}
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virtual ~Sampler();
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// Sample a single value
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virtual int64_t Sample() const = 0;
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// The probability that a single call to Sample() returns the given value.
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virtual float Probability(int64_t value) const = 0;
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int64_t range() { return range_; }
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protected:
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const int64_t range_;
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unsigned int seed_;
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};
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/**
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* Sample integers from [0, range).
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* And the distribution function is:
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* P(x) = 1 / range
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*/
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class UniformSampler : public Sampler {
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public:
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explicit UniformSampler(int64_t range, unsigned int seed = 0UL);
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~UniformSampler() override {}
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int64_t Sample() const override;
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float Probability(int64_t value) const override;
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private:
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const float inv_range_;
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std::shared_ptr<std::mt19937_64> random_engine_;
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std::shared_ptr<std::uniform_int_distribution<>> dist_;
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};
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/**
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* Sample integers from [0, range).
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* And the distribution function is:
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* P(x) = (1/ln(range+1)) * ln(1 + 1/(x + 1))
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*/
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class LogUniformSampler : public Sampler {
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public:
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explicit LogUniformSampler(int64_t range, unsigned int seed = 0UL);
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~LogUniformSampler() override {}
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int64_t Sample() const override;
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float Probability(int64_t value) const override;
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private:
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const float log_range_;
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std::shared_ptr<std::mt19937_64> random_engine_;
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std::shared_ptr<std::uniform_real_distribution<>> dist_;
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};
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/**
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* Sample integers from [0, range) from custom distribution.
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*/
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class CustomSampler : public Sampler {
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public:
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explicit CustomSampler(int64_t range, const float* probabilities,
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const int* alias, const float* alias_probabilities,
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unsigned int seed = 0UL);
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~CustomSampler() override {}
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int64_t Sample() const override;
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float Probability(int64_t value) const override;
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private:
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const float* alias_probs_;
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const int* alias_;
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const float* probs_;
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const int exceptional_val = -1;
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std::shared_ptr<std::mt19937> random_engine_;
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std::shared_ptr<std::uniform_real_distribution<>> real_dist_;
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std::shared_ptr<std::uniform_int_distribution<>> int_dist_;
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};
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} // namespace math
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} // namespace operators
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} // namespace paddle
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