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75 lines (59 loc) · 2.14 KB
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// Copyright 2018 Google LLC
//
// 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.
#ifndef CC_RANDOM_H_
#define CC_RANDOM_H_
#include <cstdint>
#include <random>
#include "absl/types/span.h"
namespace minigo {
// The C++ random library functionality is about as user friendly as its time
// library.
class Random {
public:
explicit Random(uint64_t seed = 0);
// Draw samples from a Dirichlet distribution.
void Dirichlet(float alpha, absl::Span<float> samples);
// Draw samples from a Dirichlet distribution.
template <typename T>
void Dirichlet(float alpha, T* array_like) {
Dirichlet(alpha, {array_like->data(), array_like->size()});
}
// Draw multiple unform random samples in the half-open range [mn, mx).
void Uniform(float mn, float mx, absl::Span<float> samples);
// Draw multiple unform random samples in the half-open range [mn, mx).
template <typename T>
void Uniform(float mn, float mx, T* array_like) {
Uniform(mn, mx, {array_like->data(), array_like->size()});
}
// Draw multiple unform random samples in the half-open range [0, 1).
template <typename T>
void Uniform(T* array_like) {
Uniform(0, 1, array_like);
}
// Returns a uniform random integer in the closed range [mn, mx].
int UniformInt(int mn, int mx) {
std::uniform_int_distribution<int> distribution(mn, mx);
return distribution(impl_);
}
// Returns a uniform random number in the half-open range [0, 1).
float operator()() {
return std::uniform_real_distribution<float>(0, 1)(impl_);
}
uint64_t seed() const { return seed_; }
private:
uint64_t seed_;
std::mt19937 impl_;
};
} // namespace minigo
#endif // CC_RANDOM_H_