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package bjc.utils.gen;
import java.util.Random;
import bjc.utils.funcdata.FunctionalList;
import bjc.utils.data.GenHolder;
/**
* Represents a random number generator where certain results are weighted more heavily than
* others.
* @author ben
*
* @param <E> The type of values that are randomly selected.
*/
public class WeightedRandom<E> {
private Random src;
private FunctionalList<Integer> probs;
private FunctionalList<E> results;
private int totalChance;
/**
* Create a new weighted random generator with the specified source of randomness
* @param sr The source of randomness to use.
*/
public WeightedRandom(Random sr) {
probs = new FunctionalList<>();
results = new FunctionalList<>();
src = sr;
}
/**
* Add a probability for a specific result to be given.
* @param chance The chance to get this result.
* @param res The result to get when the chance comes up.
*/
public void addProb(int chance, E res) {
probs.add(chance);
results.add(res);
totalChance += chance;
}
/**
* Generate a weighted random value.
* @return A random value selected in a weighted fashion.
*/
public E genVal() {
GenHolder<Integer> v = new GenHolder<>(src.nextInt(totalChance));
GenHolder<E> res = new GenHolder<E>();
GenHolder<Boolean> bl = new GenHolder<>(true);
probs.forEachIndexed((i, p) -> {
if (bl.held) {
if (v.held < p) {
res.held = results.getByIndex(i);
bl.held = false;
} else {
v.held -= p;
}
}
});
return res.held;
}
}
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