Package org.uma.jmetal.operator.mutation.impl

Class PowerLawMutation

java.lang.Object

org.uma.jmetal.operator.mutation.impl.PowerLawMutation

All Implemented Interfaces:

Serializable, MutationOperator<DoubleSolution>, Operator<DoubleSolution,DoubleSolution>

public class PowerLawMutation
extends Object
implements MutationOperator<DoubleSolution>

This class implements a power-law mutation operator for real-valued solutions. The power-law distribution produces heavy-tailed perturbations that can occasionally create large jumps while favoring smaller perturbations, which is beneficial for both exploration and exploitation in optimization.

The mutation follows the formula: tempDelta = rnd^(-delta) deltaq = 0.5 * (rnd - 0.5) * (1 - tempDelta) newValue = oldValue + deltaq * (upperBound - lowerBound)

Parameters:

• mutationProbability: The probability of mutating each variable. Must be in [0, 1].
• delta: The power-law exponent parameter (controls distribution shape). Must be positive (> 0). Typical values range from 0.1 to 10.0:
  • Values invalid input: '<' 1.0 create more uniform distributions with moderate perturbations
  • Values around 1.0 provide balanced exploration/exploitation
  • Values > 1.0 create heavy-tailed distributions favoring small perturbations with occasional large jumps

Code generated by Claude Sonnet 4

Author:

Antonio J. Nebro.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
PowerLawMutation()	Constructor with default parameters
PowerLawMutation(double mutationProbability, double delta)	Constructor
PowerLawMutation(double mutationProbability, double delta, RepairDoubleSolution solutionRepair)	Constructor
PowerLawMutation(double mutationProbability, double delta, RepairDoubleSolution solutionRepair, RandomGenerator<Double> randomGenerator)	Constructor

Method Summary

Modifier and Type	Method	Description
double	delta()	Get the delta parameter
void	delta(double delta)	Set the delta parameter
DoubleSolution	execute(DoubleSolution solution)	Execute the mutation operation
double	mutationProbability()	Get the mutation probability
void	mutationProbability(double mutationProbability)	Set the mutation probability
RepairDoubleSolution	solutionRepair()	Get the solution repair strategy
void	solutionRepair(RepairDoubleSolution solutionRepair)	Set the solution repair strategy
String	toString()	Get string representation of the operator

Methods inherited from class java.lang.Object

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

Constructor Details

PowerLawMutation

public PowerLawMutation()

Constructor with default parameters

PowerLawMutation

public PowerLawMutation(double mutationProbability,
 double delta)

Constructor

Parameters:

mutationProbability - The probability of mutating each variable

delta - The power-law exponent parameter (controls distribution shape)

PowerLawMutation

public PowerLawMutation(double mutationProbability,
 double delta,
 RepairDoubleSolution solutionRepair)

Constructor

Parameters:

mutationProbability - The probability of mutating each variable

delta - The power-law exponent parameter (controls distribution shape)

solutionRepair - The repair strategy for out-of-bounds values

PowerLawMutation

public PowerLawMutation(double mutationProbability,
 double delta,
 RepairDoubleSolution solutionRepair,
 RandomGenerator<Double> randomGenerator)

Constructor

Parameters:

mutationProbability - The probability of mutating each variable

delta - The power-law exponent parameter (controls distribution shape)

solutionRepair - The repair strategy for out-of-bounds values

randomGenerator - The random number generator

Method Details

execute

public DoubleSolution execute(DoubleSolution solution)

Execute the mutation operation

Specified by:

execute in interface MutationOperator<DoubleSolution>

Specified by:

execute in interface Operator<DoubleSolution,DoubleSolution>

Parameters:

solution - The solution to be mutated

Returns:

The mutated solution

mutationProbability

public double mutationProbability()

Get the mutation probability

Specified by:

mutationProbability in interface MutationOperator<DoubleSolution>

Returns:

The mutation probability

mutationProbability

public void mutationProbability(double mutationProbability)

Set the mutation probability

Parameters:

mutationProbability - The new mutation probability

delta

public double delta()

Get the delta parameter

Returns:

The delta parameter

delta

public void delta(double delta)

Set the delta parameter

Parameters:

delta - The new delta parameter

solutionRepair

public RepairDoubleSolution solutionRepair()

Get the solution repair strategy

Returns:

The solution repair strategy

solutionRepair

public void solutionRepair(RepairDoubleSolution solutionRepair)

Set the solution repair strategy

Parameters:

solutionRepair - The new solution repair strategy

toString

public String toString()

Get string representation of the operator

Overrides:

toString in class Object

Returns:

String representation