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51 lines (42 loc) · 1.4 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.
#include "cc/random.h"
#include "absl/time/clock.h"
#include "absl/time/time.h"
namespace minigo {
namespace {
uint64_t ChooseSeed(uint64_t seed) {
return seed != 0 ? seed : absl::ToUnixMicros(absl::Now());
}
} // namespace
Random::Random(uint64_t seed) : seed_(ChooseSeed(seed)), impl_(seed_) {}
void Random::Dirichlet(float alpha, absl::Span<float> samples) {
std::gamma_distribution<float> distribution(alpha);
float sum = 0;
for (float& sample : samples) {
sample = distribution(impl_);
sum += sample;
}
float norm = 1 / sum;
for (float& sample : samples) {
sample *= norm;
}
}
void Random::Uniform(float mn, float mx, absl::Span<float> samples) {
std::uniform_real_distribution<float> distribution(mn, mx);
for (float& sample : samples) {
sample = distribution(impl_);
}
}
} // namespace minigo