edu.snu.leader.hierarchy.simple.SimpleDistanceUpdateStrategy.java Source code

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Here is the source code for edu.snu.leader.hierarchy.simple.SimpleDistanceUpdateStrategy.java

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/*
 *  The Bio-inspired Leadership Toolkit is a set of tools used to
 *  simulate the emergence of leaders in multi-agent systems.
 *  Copyright (C) 2014 Southern Nazarene University
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package edu.snu.leader.hierarchy.simple;

// Imports
import org.apache.commons.lang.Validate;
import org.apache.log4j.Logger;
import java.util.Iterator;
import java.util.Properties;

/**
 * SimpleDistanceUpdateStrategy
 *
 * TODO Class description
 *
 * @author Brent Eskridge
 * @version $Revision$ ($Author$)
 */
public class SimpleDistanceUpdateStrategy implements UpdateStrategy {
    /** Our logger */
    private static final Logger _LOG = Logger.getLogger(SimpleDistanceUpdateStrategy.class.getName());

    /** Parameter key for the motivation increase due to time */
    private static final String _MOTIVATION_TIME_INCREASE_KEY = "motivation-time-increase";

    /** Parameter key for the motivation increase due to the activity of a neighbor */
    private static final String _MOTIVATION_NEIGHBOR_INCREASE_KEY = "motivation-neighbor-increase";

    /** The increase in motivation due to time */
    private float _motivationTimeIncrease = 0.0f;

    /** The increase in motivation due to the activity of a neighbor */
    private float _motivationNeighborIncrease = 0.0f;

    /**
     * Initializes this update strategy
     *
     * @param simState The simulation state
     * @see edu.snu.leader.hierarchy.simple.UpdateStrategy#initialize(edu.snu.leader.hierarchy.simple.SimulationState)
     */
    @Override
    public void initialize(SimulationState simState) {
        _LOG.trace("Entering initialize( simState )");

        // Get the simulation properties
        Properties props = simState.getProps();

        // Get the motivation increase due to time
        String motivationTimeIncrease = props.getProperty(_MOTIVATION_TIME_INCREASE_KEY);
        Validate.notEmpty(motivationTimeIncrease,
                "Motivation increase due to time is required (key=" + _MOTIVATION_TIME_INCREASE_KEY + ")");
        _motivationTimeIncrease = Float.parseFloat(motivationTimeIncrease);

        // Get the motivation increase due to neighbor activity
        String motivationNeighborIncrease = props.getProperty(_MOTIVATION_NEIGHBOR_INCREASE_KEY);
        Validate.notEmpty(motivationNeighborIncrease,
                "Motivation increase due to activity of a neighbor is required (key="
                        + _MOTIVATION_NEIGHBOR_INCREASE_KEY + ")");
        _motivationNeighborIncrease = Float.parseFloat(motivationNeighborIncrease);

        // Log the values
        _LOG.debug("_motivationTimeIncrease=[" + _motivationTimeIncrease + "] _motivationNeighborIncrease=["
                + _motivationNeighborIncrease + "]");

        _LOG.trace("Leaving initialize( simState )");
    }

    /**
     * Updates the state of the given individual.  This strategy specifies
     * how exactly the update will be done.
     *
     * @param ind
     * @param simState
     * @see edu.snu.leader.hierarchy.simple.UpdateStrategy#update(edu.snu.leader.hierarchy.simple.Individual, edu.snu.leader.hierarchy.simple.SimulationState)
     */
    @Override
    public void update(Individual ind, SimulationState simState) {
        // If the individual is active, bail
        if (ind.isActive()) {
            return;
        }

        // Get the individual's motivation
        float motivation = ind.getMotivation();

        // Add the increase in motivation due to time
        motivation += _motivationTimeIncrease;

        // Iterate through the individual's nearest neighbors
        Iterator<Neighbor> neighborIter = ind.getNearestNeighbors().iterator();
        while (neighborIter.hasNext()) {
            Neighbor neighbor = neighborIter.next();

            // Is the neighbor active?
            if (neighbor.getIndividual().isActive()) {
                // Yup, get their contribution
                float distance = neighbor.getDistance() + 1;
                motivation += _motivationNeighborIncrease / (distance * distance);
            }
        }

        // Store the updated motivation
        ind.setMotivation(motivation);
    }

}