net.sourceforge.cilib.coevolution.cooperative.problemdistribution.RandomAlgorithmImperfectSplitDistribution Maven / Gradle / Ivy

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/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */
package net.sourceforge.cilib.coevolution.cooperative.problemdistribution;

import com.google.common.base.Preconditions;
import java.util.List;
import net.sourceforge.cilib.algorithm.Algorithm;
import net.sourceforge.cilib.algorithm.iterator.RandomAlgorithmIterator;
import net.sourceforge.cilib.algorithm.population.PopulationBasedAlgorithm;
import net.sourceforge.cilib.coevolution.cooperative.CooperativeCoevolutionAlgorithm;
import net.sourceforge.cilib.coevolution.cooperative.problem.CooperativeCoevolutionProblemAdapter;
import net.sourceforge.cilib.coevolution.cooperative.problem.DimensionAllocation;
import net.sourceforge.cilib.coevolution.cooperative.problem.SequentialDimensionAllocation;
import net.sourceforge.cilib.problem.Problem;
import net.sourceforge.cilib.type.types.container.Vector;

/**
 * This {@linkplain ProblemDistributionStrategy} performs a split by assigning a sequential portion of the varying length to each participating {@linkplain PopulationBasedAlgorithm}. Defaults into a
 * split of equal sizes if possible.
 * The order in which the algorithms are assigned is generated randomly.
 */
public class RandomAlgorithmImperfectSplitDistribution implements
        ProblemDistributionStrategy {

    /**
     * Splits up the given {@link OptimisationProblem} into sub-problems, where each sub problem contains a sequential (non-uniform sized) portion of the problem vector, and assigns them to all the participating {@link Algorithm}s.
     * This implementation assigns a portion of length dimensionality/number of populations + 1 to dimensionality % number of populations of the participating populations.
     * The order in which the algorithms are assigned is generated randomly.
     * @param populations The list of participating {@linkplain PopulationBasedAlgorithm}s.
     * @param problem The problem that needs to be re-distributed.
     * @param context The context vector maintained by the {@linkplain CooperativeCoevolutionAlgorithm}.
     */
    public void performDistribution(List populations,
            Problem problem, Vector context) {
        Preconditions.checkArgument(populations.size() >= 2,
                "There should at least be two Cooperating populations in a Cooperative Algorithm");

        int dimension = problem.getDomain().getDimension() / populations.size();
        int oddDimensions = problem.getDomain().getDimension() % populations.size();
        int i = 0;
        int offset = 0;
        RandomAlgorithmIterator iterator = new RandomAlgorithmIterator(populations);
        while (iterator.hasNext()) {
            int actualDimension = dimension;
            if (i < oddDimensions) {
                actualDimension++;
            }

            DimensionAllocation problemAllocation = new SequentialDimensionAllocation(offset, actualDimension);
            iterator.next().setOptimisationProblem(new CooperativeCoevolutionProblemAdapter(problem, problemAllocation, context));
            offset += actualDimension;

            ++i;
        }
    }
}