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71 lines
2.6 KiB
71 lines
2.6 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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#include "paddle/fluid/operators/math/sampler.h"
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namespace paddle {
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namespace random {
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Sampler::~Sampler() {}
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UniformSampler::UniformSampler(int64 range)
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: Sampler(range), inv_range_(1.0 / range) {
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random_engine_ = std::make_shared<std::mt19937>(seed_);
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dist_ = std::make_shared<std::uniform_int_distribution<>>(0, range);
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}
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UniformSampler::UniformSampler(int64 range, unsigned int seed)
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: Sampler(range, seed), inv_range_(1.0 / range) {
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random_engine_ = std::make_shared<std::mt19937>(seed_);
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dist_ = std::make_shared<std::uniform_int_distribution<>>(0, range);
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}
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int64 UniformSampler::Sample() const { return (*dist_)(*random_engine_); }
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float UniformSampler::Probability(int64 value) const { return inv_range_; }
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LogUniformSampler::LogUniformSampler(int64 range)
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: Sampler(range), log_range_(log(range + 1)) {
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random_engine_ = std::make_shared<std::mt19937>(seed_);
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dist_ = std::make_shared<std::uniform_real_distribution<>>(0, 1);
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}
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LogUniformSampler::LogUniformSampler(int64 range, unsigned int seed)
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: Sampler(range, seed), log_range_(log(range + 1)) {
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random_engine_ = std::make_shared<std::mt19937>(seed_);
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dist_ = std::make_shared<std::uniform_real_distribution<>>(0, 1);
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}
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int64 LogUniformSampler::Sample() const {
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// Got Log Uniform distribution from uniform distribution by
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// inverse_transform_sampling method
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// More details:
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// https://wanghaoshuang.github.io/2017/11/Log-uniform-distribution-sampler/
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const int64 value =
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static_cast<int64>(exp((*dist_)(*random_engine_) * log_range_)) - 1;
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// Mathematically, value should be <= range_, but might not be due to some
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// floating point roundoff, so we mod by range_.
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return value % range_;
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}
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float LogUniformSampler::Probability(int64 value) const {
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// Given f(x) = 1/[(x+1) * log_range_]
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// The value's probability is integral of f(x) from value to (value + 1)
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// More details:
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// https://wanghaoshuang.github.io/2017/11/Log-uniform-distribution-sampler
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return (log((value + 2.0) / (value + 1.0))) / log_range_;
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}
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} // namespace random
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} // namespace paddle
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