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A library of composable components enabling simpler Computational Intelligence
There is a newer version: 0.8
/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */
package net.sourceforge.cilib.pso.dynamic.responsestrategies;

import java.util.List;
import net.sourceforge.cilib.algorithm.population.PopulationBasedAlgorithm;
import net.sourceforge.cilib.entity.Entity;
import net.sourceforge.cilib.nn.NeuralNetwork;
import net.sourceforge.cilib.nn.architecture.builder.LayerConfiguration;
import net.sourceforge.cilib.problem.nn.NNDataTrainingProblem;
import net.sourceforge.cilib.pso.dynamic.DynamicParticle;
import net.sourceforge.cilib.type.types.Bounds;
import net.sourceforge.cilib.type.types.Real;

/**
 * This reaction strategy adds new dimensions, to the particle's search space,
 * corresponding to the new weights added to a cascade network when it is expanded
 * by one neuron in a new hidden layer. The new dimensions in the position,
 * velocity and personal best vectors are set to Double.NaN to indicate that
 * they need to be initialised.
 *
 * @param  some {@link PopulationBasedAlgorithm population based algorithm}
 */
public class CascadeNetworkExpansionReactionStrategy extends EnvironmentChangeResponseStrategy {
    public CascadeNetworkExpansionReactionStrategy() {
    }

    public CascadeNetworkExpansionReactionStrategy(CascadeNetworkExpansionReactionStrategy rhs) {
        super(rhs);
    }

    @Override
    public CascadeNetworkExpansionReactionStrategy getClone() {
        return new CascadeNetworkExpansionReactionStrategy(this);
    }

    /**
     * Adds a single neuron to a new hidden layer in the cascade network and adds
     * the new dimensions to the particles, initialised as Double.NaN.
     *
     * {@inheritDoc}
     */
    @Override
    public void performReaction(E algorithm) {
        NNDataTrainingProblem problem = (NNDataTrainingProblem)algorithm.getOptimisationProblem();
        NeuralNetwork network = problem.getNeuralNetwork();

        //add one new neuron to a new hidden layer
        LayerConfiguration targetLayerConfiguration = new LayerConfiguration();
        targetLayerConfiguration.setSize(1);
        network.getArchitecture().getArchitectureBuilder().addLayer(network.getArchitecture().getArchitectureBuilder().getLayerConfigurations().size()-1, targetLayerConfiguration);
        network.initialise();

        //add new weights to all the particles in a manner that preserves the old weights
        List particles = algorithm.getTopology();
        int hiddenLayerSize = network.getArchitecture().getArchitectureBuilder().getLayerConfigurations().size() -2;
        int outputLayerSize = network.getArchitecture().getArchitectureBuilder().getLayerConfigurations().get(2).getSize();
        int inputLayerSize = network.getArchitecture().getArchitectureBuilder().getLayerConfigurations().get(0).getSize();
        if (network.getArchitecture().getArchitectureBuilder().getLayerConfigurations().get(0).isBias()) {
            inputLayerSize += 1;
        }
        for (Entity curParticle : particles) {
            DynamicParticle curDynamicParticle = (DynamicParticle)curParticle;
            Bounds bounds = curDynamicParticle.getPosition().get(0).getBounds();

            //add weights of new neuron
            int addPosition = inputLayerSize * (hiddenLayerSize-1);
            addPosition += (hiddenLayerSize-2)*(hiddenLayerSize-1)/2;
            for (int i = 0; i < inputLayerSize + hiddenLayerSize-1; ++i) {
                curDynamicParticle.getPosition().insert(addPosition, Real.valueOf(Double.NaN, bounds));
                curDynamicParticle.getBestPosition().insert(addPosition, Real.valueOf(Double.NaN, bounds));
                curDynamicParticle.getVelocity().insert(addPosition, Real.valueOf(Double.NaN, bounds));
            }

            //add weights between new neuron and output layer
            int startAddPosition = inputLayerSize * hiddenLayerSize;
            startAddPosition += (hiddenLayerSize-1)*hiddenLayerSize/2;
            for (int curOutput = 0; curOutput < outputLayerSize; ++curOutput) {
                addPosition = startAddPosition + (curOutput+1)*(inputLayerSize + hiddenLayerSize) -1;

                curDynamicParticle.getPosition().insert(addPosition, Real.valueOf(Double.NaN, bounds));
                curDynamicParticle.getBestPosition().insert(addPosition, Real.valueOf(Double.NaN, bounds));
                curDynamicParticle.getVelocity().insert(addPosition, Real.valueOf(Double.NaN, bounds));
            }
        }
    }
}