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2026-07-13 12:40:42 +08:00

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// Copyright (c) 2024 PaddlePaddle 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.
#pragma once
#include <cstdint>
#include <memory>
#include <random>
#include <vector>
#include "paddle/phi/core/enforce.h"
namespace phi {
namespace math {
// TODO(wanghaoshuang): Support for GPU
/**
* Sample integers from [0, range).
*/
class Sampler {
public:
explicit Sampler(int64_t range, unsigned int seed = 0UL) : range_(range) {
PADDLE_ENFORCE_GT(
range,
0,
common::errors::InvalidArgument(
"Range should be greater than 0, but received %d.", range));
if (seed == 0) {
std::random_device r;
seed_ = r();
} else {
seed_ = seed;
}
}
virtual ~Sampler();
// Sample a single value
virtual int64_t Sample() const = 0;
// The probability that a single call to Sample() returns the given value.
virtual float Probability(int64_t value) const = 0;
int64_t range() { return range_; }
protected:
const int64_t range_;
unsigned int seed_;
};
/**
* Sample integers from [0, range).
* And the distribution function is:
* P(x) = 1 / range
*/
class UniformSampler : public Sampler {
public:
explicit UniformSampler(int64_t range, unsigned int seed = 0UL);
~UniformSampler() override {}
int64_t Sample() const override;
float Probability(int64_t value) const override;
private:
const float inv_range_;
std::shared_ptr<std::mt19937_64> random_engine_;
std::shared_ptr<std::uniform_int_distribution<>> dist_;
};
/**
* Sample integers from [0, range).
* And the distribution function is:
* P(x) = (1/ln(range+1)) * ln(1 + 1/(x + 1))
*/
class LogUniformSampler : public Sampler {
public:
explicit LogUniformSampler(int64_t range, unsigned int seed = 0UL);
~LogUniformSampler() override {}
int64_t Sample() const override;
float Probability(int64_t value) const override;
private:
const float log_range_;
std::shared_ptr<std::mt19937_64> random_engine_;
std::shared_ptr<std::uniform_real_distribution<>> dist_;
};
/**
* Sample integers from [0, range) from custom distribution.
*/
class CustomSampler : public Sampler {
public:
explicit CustomSampler(int64_t range,
const float* probabilities,
const int* alias,
const float* alias_probabilities,
unsigned int seed = 0UL);
~CustomSampler() override {}
int64_t Sample() const override;
float Probability(int64_t value) const override;
private:
const float* alias_probs_;
const int* alias_;
const float* probs_;
const int exceptional_val = -1;
std::shared_ptr<std::mt19937_64> random_engine_;
std::shared_ptr<std::uniform_real_distribution<>> real_dist_;
std::shared_ptr<std::uniform_int_distribution<>> int_dist_;
};
} // namespace math
} // namespace phi