edu.snu.leader.spatial.calculator.CompactSigmoidSueurDecisionProbabilityCalculator.java Source code

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Here is the source code for edu.snu.leader.spatial.calculator.CompactSigmoidSueurDecisionProbabilityCalculator.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.spatial.calculator;

// Imports
import edu.snu.leader.spatial.DecisionType;
import edu.snu.leader.spatial.SimulationState;

import org.apache.commons.lang.Validate;
import org.apache.log4j.Logger;

import java.util.Properties;

/**
 * CompactSigmoidSueurDecisionProbabilityCalculator
 *
 * TODO Class description
 *
 * @author Brent Eskridge
 * @version $Revision$ ($Author$)
 */
public class CompactSigmoidSueurDecisionProbabilityCalculator extends AbstractSueurDecisionProbabilityCalculator {

    /** Our logger */
    private static final Logger _LOG = Logger
            .getLogger(CompactSigmoidSueurDecisionProbabilityCalculator.class.getName());

    /** Key for modifying the sigmoid slope value */
    private final String _SIGMOID_SLOPE_VALUE_KEY = "sigmoid-slope-value";

    /** Sigmoid slope value */
    private float _sigmoidSlopeValue = 0.0f;

    /**
     * Initializes the calculator
     *
     * @param simState The simulation's state
     * @see edu.snu.leader.spatial.DecisionProbabilityCalculator#initialize(edu.snu.leader.spatial.SimulationState)
     */
    @Override
    public void initialize(SimulationState simState) {
        _LOG.trace("Entering initialize( simState )");

        // Call superclass implementation
        super.initialize(simState);

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

        // Get the sigmoid slope value
        String sigmoidSlopeValueStr = props.getProperty(_SIGMOID_SLOPE_VALUE_KEY);
        Validate.notEmpty(sigmoidSlopeValueStr,
                "Sigmoid slope value (Key =" + _SIGMOID_SLOPE_VALUE_KEY + ") may not be empty ");
        _sigmoidSlopeValue = Float.parseFloat(sigmoidSlopeValueStr);
        _LOG.info("Using _sigmoidSlopeValue = [" + _sigmoidSlopeValue + "]");

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

    /**
     * Calculates k coefficient for the collective movement equations
     *
     * @param value
     * @return The k coefficient
     * @see edu.snu.leader.spatial.calculator.AbstractSueurDecisionProbabilityCalculator#calculateK(float)
     */
    @Override
    protected float calculateK(float value, DecisionType type) {
        float k = 0.0f;

        // If it is initiation or following, use a range of [0.1,1.9]
        if (DecisionType.INITIATE.equals(type) || DecisionType.FOLLOW.equals(type)) {
            k = 0.1f + (1.8f * (1.0f / (1.0f + (float) Math.exp((0.5f - value) * _sigmoidSlopeValue))));
        }
        // Otherwise, if it is a cancel, use a more compact range
        else if (DecisionType.CANCEL.equals(type)) {
            //            k = 0.6f + ( 0.8f * ( 1.0f / (1.0f +
            //                    (float) Math.exp( (0.5f-value) * _sigmoidSlopeValue) ) ) );
            k = 0.59623023f
                    + (0.80753954f * (1.0f / (1.0f + (float) Math.exp((0.5f - value) * _sigmoidSlopeValue))));
        }

        return k;
    }

}