问题
I have a problem where I want to generate a set of random integer values between 1 and 5 inclusive using a probability distribution.
Poisson and Inverse Gamma are two distributions that show the characteristics I am after (majority at mean, less higher numbers) that I have found.
I am looking at using Apache Commons Math but I wasn't sure how to generate the numbers I wanted using the distributions available.
回答1:
From your problem description, it sounds like you actually want a sample generated from a discrete probability distribution, and you can use EnumeratedIntegerDistribution for this purpose. Choose appropriate probabilities for each of your integers, maybe something like the following would meet your needs:
int[] numsToGenerate = new int[] { 1, 2, 3, 4, 5 };
double[] discreteProbabilities = new double[] { 0.1, 0.25, 0.3, 0.25, 0.1 };
EnumeratedIntegerDistribution distribution =
new EnumeratedIntegerDistribution(numsToGenerate, discreteProbabilities);
int numSamples = 100;
int[] samples = distribution.sample(numSamples);
Just tweak the discreteProbabilities
values to whatever you require.
回答2:
I would just produce uniformly distributed random numbers then pass them into the distribution function you want, so if the distribution function was x^2
import java.util.ArrayList;
import java.util.Random;
public class Test{
public static void main(String args[]){
Test t=new Test();
}
public Test(){
Random rnd=new Random();
ArrayList<Double> data=new ArrayList<Double>();
for(int i=0;i<1000;i++){
data.add(useFunction(rnd.nextDouble()));
}
}
public double useFunction(double in){
return in*in;
}
}
来源:https://stackoverflow.com/questions/16435639/generating-random-integers-within-range-with-a-probability-distribution