Class WeightedHybridCrossover<T>

  • Type Parameters:
    T - The type of object used to represent candidate solutions to the problem.
    All Implemented Interfaces:
    Splittable<CrossoverOperator<T>>, CrossoverOperator<T>

    public final class WeightedHybridCrossover<T>
    extends Object
    implements CrossoverOperator<T>

    A WeightedHybridCrossover enables using multiple crossover operators, such that each time the cross(T, T) method is called, a randomly chosen crossover operator is applied to the candidate solutions. The random choice of crossover operator is weighted proportionately based on an array of weights passed upon construction.

    Consider the following weights: w = [ 1, 2, 3]. In this example, the first crossover operator will be used with probability 0.167, the second crossover operator will be used with probability 2/6 = 0.333, and the third crossover operator will be used with probability 3/6 = 0.5.

    • Constructor Detail

      • WeightedHybridCrossover

        public WeightedHybridCrossover​(Collection<? extends CrossoverOperator<T>> ops,
                                       int[] weights)
        Constructs a WeightedHybridCrossover from a Collection of CrossoverOperators.
        Parameters:
        ops - A Collection of CrossoverOperators.
        weights - The array of weights, whose length must be equal to ops.size(). Every element of weights must be greater than 0.
        Throws:
        IllegalArgumentException - if ops doesn't contain any CrossoverOperators.
        IllegalArgumentException - if ops.size() is not equal to weights.length.
        IllegalArgumentException - if any weights are non-positive.
    • Method Detail

      • cross

        public void cross​(T c1,
                          T c2)
        Description copied from interface: CrossoverOperator
        Performs a crossover for an evolutionary algorithm, such that crossover forms two children from two parents. Implementations of this method modify the parameters, transforming the parents into the children.
        Specified by:
        cross in interface CrossoverOperator<T>
        Parameters:
        c1 - A candidate solution subject to the crossover. This method changes the state of c1.
        c2 - A candidate solution subject to the crossover. This method changes the state of c2.
      • split

        public WeightedHybridCrossover<T> split()
        Description copied from interface: Splittable
        Generates 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 Copyable interface. 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.
        Specified by:
        split in interface Splittable<T>
        Returns:
        A functionally identical copy of the object, or a reference to this if it is both safe and efficient for multiple threads to share a single instance of this Splittable object.