Package se.liu.ida.hefquin.base.utils

Class RandomizedSelection<T extends RandomizedSelection.WeightedObject>

java.lang.Object

se.liu.ida.hefquin.base.utils.RandomizedSelection<T>

public class RandomizedSelection<T extends RandomizedSelection.WeightedObject>
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected class	RandomizedSelection.MyIterator
static interface	RandomizedSelection.WeightedObject

Constructor Summary

Constructors

Constructor	Description
RandomizedSelection()

Method Summary

Modifier and Type	Method	Description
Iterator<T>	getRandomlyPickingIterator(Set<T> elements)	Returns an infinite iterator that can be used to continuously pick elements from the given set at random, where the weights of the elements determine their respective probability to be picked.
T	pickOne(Set<T> elements)	Picks one of the elements from the given set by random and returns that element, where the weights of the elements determine their respective probability to be picked.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

RandomizedSelection

public RandomizedSelection()

Method Details

pickOne

public T pickOne(Set<T> elements)

Picks one of the elements from the given set by random and returns that element, where the weights of the elements determine their respective probability to be picked. That is, if an element E in the set has a weight of X and the sum of all weights of all elements in the set is Y, then the probability of element E is X/Y. Note that this method needs to populate an internal data structure. Therefore, if you want to pick multiple times (independent from one another), it is better to do so via an iterator that can be obtained with getRandomlyPickingIterator(Set).

getRandomlyPickingIterator

public Iterator<T> getRandomlyPickingIterator(Set<T> elements)

Returns an infinite iterator that can be used to continuously pick elements from the given set at random, where the weights of the elements determine their respective probability to be picked. That is, if an element E in the set has a weight of X and the sum of all weights of all elements in the set is Y, then the probability of element E is X/Y. The probabilities are not affected by which elements have been picked before.