- Type Parameters:
T- The type of object used to represent candidate solutions to the problem.
- All Implemented Interfaces:
public final class WeightedHybridUndoableMutation<T> extends Object implements UndoableMutationOperator<T>
A WeightedHybridMutation enables using multiple mutation operators for the search, such that each time the
mutate(T)method is called, a randomly chosen mutation operator is applied to the candidate solution. The random choice of mutation operator is weighted proportionately based on an array of weights passed upon construction. This implementation supports the
Consider the following weights: w = [ 1, 2, 3]. In this example, the first mutation operator will be used with probability 0.167, the second mutation operator will be used with probability 2/6 = 0.333, and the third mutation operator will be used with probability 3/6 = 0.5.
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
mutate(T c)Mutates a candidate solution to a problem, by randomly modifying its state.
split()Generates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms.
undo(T c)Returns a candidate solution to its previous state prior to the most recent mutation performed.
public WeightedHybridUndoableMutation(Collection<? extends UndoableMutationOperator<T>> mutationOps, int weights)Constructs a WeightedHybridUndoableMutation from a Collection of UndoableMutationOperator.
mutationOps- A Collection of UndoableMutationOperator.
weights- The array of weights, whose length must be equal to mutationOps.size(). Every element of weights must be greater than 0.
IllegalArgumentException- if mutationOps doesn't contain any UndoableMutationOperator.
IllegalArgumentException- if mutationOps.size() is not equal to weights.length.
IllegalArgumentException- if any weights are non-positive.
public void mutate(T c)Description copied from interface:
MutationOperatorMutates a candidate solution to a problem, by randomly modifying its state. The mutant that is produced is in the local neighborhood of the original candidate solution.
public void undo(T c)Description copied from interface:
Returns a candidate solution to its previous state prior to the most recent mutation performed.
For example, consider the following. Let c' be the current state of c. Let c'' be the state of c after mutate(c); If we then call undo(c), the state of c should revert back to c'.
The behavior of undo is undefined if c is altered by some other process between the calls to mutate and undo. The behavior is also undefined if a different candidate is given to undo then the last given to mutate. For example, if the following two statements are executed, mutate(c); undo(d);, the effect on d is undefined as it wasn't the most recently mutated candidate solution.
public WeightedHybridUndoableMutation<T> split()Description copied from interface:
SplittableGenerates a functionally identical copy of this object, for use in multithreaded implementations of search algorithms. The state of the object that is returned may or may not be identical to that of the original. Thus, this is a distinct concept from the functionality of the
Copyableinterface. Classes that implement this interface must ensure that the object returned performs the same functionality, and that it does not share any state data that would be either unsafe or inefficient for concurrent access by multiple threads. The split method is allowed to simply return the this reference, provided that it is both safe and efficient for multiple threads to share a single copy of the Splittable object. The intention is to provide a multithreaded search with the capability to provide spawned threads with their own distinct search operators. Such multithreaded algorithms can call the split method for each thread it spawns to generate a functionally identical copy of the operator, but with independent state.