Package org.uma.jmetal.util.sequencegenerator.impl

Class RandomPermutationCycle

java.lang.Object

org.uma.jmetal.util.sequencegenerator.impl.RandomPermutationCycle

All Implemented Interfaces:

SequenceGenerator<Integer>

public class RandomPermutationCycle
extends Object
implements SequenceGenerator<Integer>

A sequence generator that produces random permutations of integers from 0 (inclusive) to the specified size (exclusive). Each time the sequence is exhausted, a new random permutation is generated.

This implementation uses an efficient algorithm to generate random permutations without repetition until all elements have been used, at which point a new random permutation is created.

Example usage:

 // Will generate sequences like: [2,0,1,3,4], [1,3,2,0,4], [4,2,0,1,3], ...
 SequenceGenerator<Integer> generator = new RandomPermutationCycle(5);
 

Author:

Antonio J. Nebro

Constructor Summary

Constructors

Constructor	Description
RandomPermutationCycle(int size)	Creates a new random permutation cycle generator.

Method Summary

Modifier and Type	Method	Description
void	generateNext()	Advances the sequence to the next value.
int	getSequenceLength()	Returns the length of the sequence before it repeats or resets.
Integer	getValue()	Returns the current value in the sequence.

Methods inherited from class java.lang.Object

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

Constructor Details

RandomPermutationCycle

public RandomPermutationCycle(int size)

Creates a new random permutation cycle generator.

Parameters:

size - the size of the permutation (must be positive)

Throws:

IllegalArgumentException - if size is not positive

Method Details

getValue

public Integer getValue()

Description copied from interface: SequenceGenerator

Returns the current value in the sequence.

Specified by:

getValue in interface SequenceGenerator<Integer>

Returns:

the current value in the sequence

generateNext

public void generateNext()

Description copied from interface: SequenceGenerator

Advances the sequence to the next value. The behavior when called after reaching the end of the sequence is implementation-dependent. Some implementations may cycle back to the beginning, while others may generate new sequences.

Specified by:

generateNext in interface SequenceGenerator<Integer>

getSequenceLength

public int getSequenceLength()

Description copied from interface: SequenceGenerator

Returns the length of the sequence before it repeats or resets.

Specified by:

getSequenceLength in interface SequenceGenerator<Integer>

Returns:

the number of unique values in the sequence before it repeats