randomDist.h

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/*
 * -------------------------------------------
 * Copyright (c) 2021 - 2024 Prashant K. Jha
 * -------------------------------------------
 * PeriDEM https://github.com/prashjha/PeriDEM
 *
 * Distributed under the Boost Software License, Version 1.0. (See accompanying
 * file LICENSE)
 */
 
#ifndef UTILS_RANDOM_H
#define UTILS_RANDOM_H
 
#include <random>
 
typedef std::mt19937 RandGenerator;
typedef std::lognormal_distribution<> LogNormalDistribution;
typedef std::uniform_real_distribution<> UniformDistribution;
typedef std::normal_distribution<> NormalDistribution;
typedef std::uniform_int_distribution<> UniformIntDistribution;
 
namespace util {
 
inline RandGenerator get_rd_gen(int seed = -1) {
 
  //return RandGenerator();
 
  if (seed < 0) {
    std::random_device rd;
    seed = rd();
  }
 
  return RandGenerator(seed);
}
 
inline std::default_random_engine get_rd_engine(int &seed) {
 
  //return std::default_random_engine();
 
  if (seed < 0) {
    std::random_device rd;
    seed = rd();
  }
 
  return std::default_random_engine(seed);
}
 
inline double transform_to_normal_dist(double mean, double std, double sample) {
  return std * sample + mean;
}
 
inline double transform_to_uniform_dist(double min, double max, double sample) {
  return min + sample * (max - min);
}
 
template<class T>
class DistributionSample {
public:
  DistributionSample(double arg1, double arg2, int seed = -1)
      : d_seed(seed), d_gen(get_rd_gen(seed)), d_dist(arg1, arg2){};
 
  DistributionSample() : d_seed(-1){};
 
  void init(double arg1, double arg2, int seed = -1) {
 
    d_seed = seed;
    d_gen = RandGenerator(get_rd_gen(seed));
    d_dist = T(arg1, arg2);
  }
 
  double operator()() {
    return d_dist(d_gen);
  }
 
  int d_seed;
 
  RandGenerator d_gen;
 
  T d_dist;
};
 
} // namespace util
 
#endif // UTILS_RANDOM_H