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Rework of Random class. Now ensures better randomness, is more performant, and has function for retrieving seed.
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Deukhoofd 2020-04-04 17:48:05 +02:00
parent 4f563e6e67
commit 6f60cd7c96
Signed by: Deukhoofd
GPG Key ID: ADF2E9256009EDCE
2 changed files with 45 additions and 38 deletions
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61
src/Random.hpp
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@ -1,76 +1,83 @@
#ifndef ARBUTILS_RANDOM_HPP #ifndef ARBUTILS_RANDOM_HPP
#define ARBUTILS_RANDOM_HPP #define ARBUTILS_RANDOM_HPP
#include <chrono>
#include <cstdint> #include <cstdint>
#include <random> #include <random>
#include <chrono>
namespace Arbutils { namespace Arbutils {
template <class RandomT> class BaseRandom { template <class RandomT> class BaseRandom {
private: private:
uint32_t _seed;
RandomT _rng; RandomT _rng;
std::uniform_real_distribution<double> _distribution;
public: public:
inline constexpr BaseRandom() inline constexpr BaseRandom() noexcept
: _rng(RandomT( : _seed(std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()) std::chrono::system_clock::now().time_since_epoch())
.count())) {} .count()),
_rng(_seed), _distribution(0.0, 1.0) {}
explicit inline constexpr BaseRandom(int32_t seed) : _rng(seed){}; explicit inline constexpr BaseRandom(uint64_t seed) noexcept
: _seed(seed), _rng(seed), _distribution(0.0, 1.0){};
/// Gets a random float between 0.0 and 1.0. /// Gets a random float between 0.0 and 1.0.
[[nodiscard]] inline constexpr float GetFloat() { [[nodiscard]] inline constexpr float GetFloat() noexcept {
return static_cast<float>(_rng()) / (static_cast<float>(std::mt19937::max() - std::mt19937::min()) - 0.5f); return static_cast<float>(GetDouble());
} }
/// Gets a random double between 0.0 and 1.0. /// Gets a random double between 0.0 and 1.0.
[[nodiscard]] inline constexpr double GetDouble() { [[nodiscard]] inline constexpr double GetDouble() noexcept {
return static_cast<double>(_rng()) / return (double) _distribution(_rng);
((static_cast<double>(std::mt19937::max()) - std::mt19937::min()) - 0.5);
} }
/// Gets a random 32 bit integer between 0 and max int. /// Gets a random 32 bit integer
[[nodiscard]] inline constexpr int32_t Get() { [[nodiscard]] inline constexpr int32_t Get() noexcept { return (int32_t)_rng(); }
return static_cast<int32_t>(GetDouble() * static_cast<float>(std::numeric_limits<int32_t>::max()));
}
/// Gets a random 32 bit integer between 0, and given max parameter. /// Gets a random 32 bit integer between 0, and given max parameter.
/// \param max The exclusive max value the random value should be. /// \param max The exclusive max value the random value should be.
[[nodiscard]] inline constexpr int32_t Get(int32_t max) { [[nodiscard]] inline int32_t Get(int32_t max) noexcept {
return static_cast<int32_t>(GetDouble() * static_cast<float>(max)); std::uniform_int_distribution<int32_t > distribution(0, max - 1);
return distribution(_rng);
} }
/// Gets a random 32 bit integer between given min and max parameters. /// Gets a random 32 bit integer between given min and max parameters.
/// \param min The inclusive min value the random value should be. /// \param min The inclusive min value the random value should be.
/// \param max The exclusive max value the random value should be. /// \param max The exclusive max value the random value should be.
[[nodiscard]] inline constexpr int32_t Get(int32_t min, int32_t max) { [[nodiscard]] inline int32_t Get(int32_t min, int32_t max) noexcept {
return static_cast<int32_t>(GetDouble() * static_cast<float>(max - min) + min); std::uniform_int_distribution<int32_t > distribution(min, max - 1);
return distribution(_rng);
} }
/// Gets a random 32 bit unsigned integer between 0 and max unsigned int. /// Gets a random 32 bit unsigned integer between 0 and max unsigned int.
[[nodiscard]] inline constexpr uint32_t GetUnsigned() { [[nodiscard]] inline constexpr uint32_t GetUnsigned() noexcept {
return static_cast<int32_t>(GetDouble() * static_cast<float>(std::numeric_limits<uint32_t>::max())); return _rng();
} }
/// Gets a random 32 bit unsigned integer between 0, and given max parameter. /// Gets a random 32 bit unsigned integer between 0, and given max parameter.
/// \param max The exclusive max value the random value should be. /// \param max The exclusive max value the random value should be.
[[nodiscard]] inline constexpr uint32_t GetUnsigned(uint32_t max) { [[nodiscard]] inline uint32_t GetUnsigned(uint32_t max) noexcept {
return static_cast<int32_t>(GetDouble() * static_cast<float>(max)); std::uniform_int_distribution<uint32_t > distribution(0, max - 1);
return distribution(_rng);
} }
/// Gets a random 32 bit unsigned integer between given min and max parameters. /// Gets a random 32 bit unsigned integer between given min and max parameters.
/// \param min The inclusive min value the random value should be. /// \param min The inclusive min value the random value should be.
/// \param max The exclusive max value the random value should be. /// \param max The exclusive max value the random value should be.
[[nodiscard]] inline constexpr uint32_t GetUnsigned(uint32_t min, uint32_t max) { [[nodiscard]] inline uint32_t GetUnsigned(uint32_t min, uint32_t max) noexcept {
return static_cast<int32_t>(GetDouble() * static_cast<float>(max - min) + min); std::uniform_int_distribution<uint32_t > distribution(min, max - 1);
return distribution(_rng);
} }
[[nodiscard]] inline constexpr uint32_t GetSeed() const noexcept { return _seed; }
}; };
class Random : public BaseRandom<std::mt19937> { class Random : public BaseRandom<std::mt19937> {
public: public:
Random() : BaseRandom() {} constexpr Random() : BaseRandom() {}
Random(int32_t seed) : BaseRandom(seed) {} constexpr Random(int32_t seed) : BaseRandom(seed) {}
}; };
} }
#endif // ARBUTILS_RANDOM_HPP #endif // ARBUTILS_RANDOM_HPP

22
tests/RandomTests.cpp
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@ -6,16 +6,16 @@
TEST_CASE("Random ints", "[Utilities]") { TEST_CASE("Random ints", "[Utilities]") {
auto rand = Arbutils::Random(10); auto rand = Arbutils::Random(10);
CHECK(rand.Get() == 1656398469); CHECK(rand.Get() == -982170359);
CHECK(rand.Get() == 641584702); CHECK(rand.Get() == 1283169405);
CHECK(rand.Get() == 44564466); CHECK(rand.Get() == 89128932);
CHECK(rand.Get() == 1062123783); CHECK(rand.Get() == 2124247567);
CHECK(rand.Get() == 1360749216); CHECK(rand.Get() == -1573468864);
CHECK(rand.Get() == 951367352); CHECK(rand.Get() == 1902734705);
CHECK(rand.Get() == 1608044094); CHECK(rand.Get() == -1078879109);
CHECK(rand.Get() == 1786516046); CHECK(rand.Get() == -721935204);
CHECK(rand.Get() == 1070535660); CHECK(rand.Get() == 2141071321);
CHECK(rand.Get() == 1252673902); CHECK(rand.Get() == -1789619491);
} }
TEST_CASE("Random ints with limit", "[Utilities]") { TEST_CASE("Random ints with limit", "[Utilities]") {
@ -93,7 +93,7 @@ TEST_CASE("Random distribution (max 0, min 2)", "[Utilities]") {
TEST_CASE("Random distribution (max 0, min 3)", "[Utilities]") { TEST_CASE("Random distribution (max 0, min 3)", "[Utilities]") {
auto rand = Arbutils::Random(10); auto rand = Arbutils::Random(10);
const int size = 100000; const int size = 500000;
int arr[size]; int arr[size];
for (size_t i = 0; i < size; i++) { for (size_t i = 0; i < size; i++) {
arr[i] = rand.Get(0, 3); arr[i] = rand.Get(0, 3);