RandomSample

The given example displays 20 random floating point numbers from a discrete distribution. It uses two different generators to achieve this. The first generator uses a particular value to initialize the seed, while the second one is using the system timer. Notice that it was necessary to divide the timer by the <em> MERSENNEDIV </em> value in order to keep the seed in the interval from 0 to 1. Since the seed of the first generator is never changed, the first 10 numbers will always remain the same. However since the second generator is initialized via the system timer, the next 10 numbers will obviously vary with each execution of the program.

Also notice the declaration of the probability array P and value array V. They are used as constructor arguments when declaring the generators to specify the probabilities P[i] associated to each value V[i] in the values table. Always make sure that the components of P sum up to 1.

#include <iostream>
#include <time.h>
#include <codecogs/statistics/distributions/discrete/discrete/randomsample.h>
using namespace std;

int main()
{
  double P[4] = {   0.4,   0.1,   0.2,   0.3 };
  double V[4] = { 1.234, 2.345, 3.456, 4.567 };
		
  Stats::Dists::Discrete::Discrete::RandomSample<double> A(4, P, V, false, 0.3416);
  Stats::Dists::Discrete::Discrete::RandomSample<double> B(4, P, false, time(0) / MERSENNEDIV);
		
  for (int i = 0; i < 20; ++i)
    cout << A.genReal() << " ";
  cout << endl;
		
  for (int i = 0; i < 20; ++i)
    cout << B.genReal() << " ";
  cout << endl;
		
  return 0;
}

Output:

4.567 1.234 4.567 1.234 4.567 3.456 1.234 2.345 1.234 1.234 1.234 3.456 3.456 2.345 2.345 3.456 4.567 3.456 1.234 2.345 
0 0 0 3 0 0 2 0 2 1 1 0 3 0 3 0 0 3 2 0