random.cpp

/*
#ifndef _RANDOM_H
#define _RANDOM_H_

#include <boost/random.hpp>
#include <ctime>
#include <cmath>

*/

#include "random.h"
using namespace std;

static boost::mt19937 generator(static_cast<unsigned> (std::time(0)));
double random_uni01() {
  boost::uniform_real<> uni_dist(0,1);
  boost::variate_generator<boost::mt19937&, boost::uniform_real<> > uni(generator, uni_dist);

  return uni();
}

// return a random number between lowest(including) and highest(excluding)
unsigned int get_a_random_number(int lowest, int highest) {
  if (highest < lowest) {
    cout << "ERROR In random_number_generator: Higher value is smaller than lower\n";
    exit(1);
  }
  unsigned int random_integer;
  int range=(highest-lowest);
  random_integer = lowest + rand()%range;
  return random_integer;
}

// return a random number between lowest(including) and highest(excluding) using boost
unsigned int boost_get_a_random_number(int lowest, int highest) {
  if (highest < lowest) {
    cout << "ERROR In random_number_generator: Higher value is smaller than lower\n";
    exit(1);
  }
  //boost::mt19937 rng; 
  boost::uniform_int<> range_dist(lowest,highest-1);
  boost::variate_generator<boost::mt19937&, boost::uniform_int<> >
           int_ran_gen(generator, range_dist);             // glues randomness with mapping
  return int_ran_gen();
}

unsigned int randomWithDiscreteProbability(const vector<double>& accum_prob_vec) {
  double x = random_uni01();
  return lower_bound(accum_prob_vec.begin(), accum_prob_vec.end(), x) - 
         accum_prob_vec.begin();
}
//#endif