Package org.uncommons.watchmaker.framework.operators

Class StringCrossover

  • All Implemented Interfaces:
    EvolutionaryOperator<String>
    public class StringCrossover
extends AbstractCrossover<String>
    Variable-point (fixed or random) cross-over for String candidates. This implementation assumes that all candidate Strings are the same length. If they are not, an exception will be thrown at runtime.

    • Constructor Detail

      • StringCrossover

        public StringCrossover()
        Default is single-point cross-over, applied to all parents.

      • StringCrossover

        public StringCrossover​(int crossoverPoints)
        Cross-over with a fixed number of cross-over points.
        Parameters:
        crossoverPoints - The constant number of cross-over points to use for all cross-over operations.

      • StringCrossover

        public StringCrossover​(int crossoverPoints,
                       Probability crossoverProbability)
        Cross-over with a fixed number of cross-over points. Cross-over may or may not be applied to a given pair of parents depending on the crossoverProbability.
        Parameters:
        crossoverPoints - The constant number of cross-over points to use for all cross-over operations.
        crossoverProbability - The probability that, once selected, a pair of parents will be subjected to cross-over rather than being copied, unchanged, into the output population.

      • StringCrossover

        public StringCrossover​(NumberGenerator<Integer> crossoverPointsVariable)
        Cross-over with a variable number of cross-over points.
        Parameters:
        crossoverPointsVariable - A random variable that provides a number of cross-over points for each cross-over operation.

      • StringCrossover

        public StringCrossover​(NumberGenerator<Integer> crossoverPointsVariable,
                       NumberGenerator<Probability> crossoverProbabilityVariable)
        Sets up a cross-over implementation that uses a variable number of cross-over points. Cross-over is applied to a proportion of selected parent pairs, with the remainder copied unchanged into the output population. The size of this evolved proportion is controlled by the crossoverProbabilityVariable parameter.
        Parameters:
        crossoverPointsVariable - A variable that provides a (possibly constant, possibly random) number of cross-over points for each cross-over operation.
        crossoverProbabilityVariable - A variable that controls the probability that, once selected, a pair of parents will be subjected to cross-over rather than being copied, unchanged, into the output population.

    • Method Detail

      • mate

        protected List<String> mate​(String parent1,
                            String parent2,
                            int numberOfCrossoverPoints,
                            Random rng)
        Perform cross-over on a pair of parents to generate a pair of offspring.
        Specified by:
        mate in class AbstractCrossover<String>
        Parameters:
        parent1 - One of two individuals that provides the source material for generating offspring.
        parent2 - One of two individuals that provides the source material for generating offspring.
        numberOfCrossoverPoints - The number of cross-overs performed on the two parents.
        rng - A source of randomness used to determine the location of cross-over points.
        Returns:
        A list containing two evolved offspring.