OutcomeNode.java

/**
 * Copyright (c) 2011, SOCIETIES Consortium (WATERFORD INSTITUTE OF TECHNOLOGY (TSSG), HERIOT-WATT UNIVERSITY (HWU), SOLUTA.NET 
 * (SN), GERMAN AEROSPACE CENTRE (Deutsches Zentrum fuer Luft- und Raumfahrt e.V.) (DLR), Zavod za varnostne tehnologije
 * informacijske družbe in elektronsko poslovanje (SETCCE), INSTITUTE OF COMMUNICATION AND COMPUTER SYSTEMS (ICCS), LAKE
 * COMMUNICATIONS (LAKE), INTEL PERFORMANCE LEARNING SOLUTIONS LTD (INTEL), PORTUGAL TELECOM INOVAÇÃO, SA (PTIN), IBM Corp., 
 * INSTITUT TELECOM (ITSUD), AMITEC DIACHYTI EFYIA PLIROFORIKI KAI EPIKINONIES ETERIA PERIORISMENIS EFTHINIS (AMITEC), TELECOM 
 * ITALIA S.p.a.(TI),  TRIALOG (TRIALOG), Stiftelsen SINTEF (SINTEF), NEC EUROPE LTD (NEC))
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
 * conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
 * SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.societies.personalisation.dianne.model;

import java.util.Iterator;

public class OutcomeNode extends Node
{
	double potential;
	double gradient;
	
	public OutcomeNode(int ID, String groupName, String nodeName)
	{
		super(ID, groupName, nodeName);
		potential = 0.0;
	}
	
	public void calculatePotential()
	{
		double tmpPotential = 0.0;
		
		Iterator<Synapse> synapses_it = synapses.iterator();
		while(synapses_it.hasNext())
		{
			Synapse nextSynapse = (Synapse)synapses_it.next();
			if(nextSynapse.getPreNode().getActive())  //the context pre-node is active
			{
				tmpPotential = tmpPotential+nextSynapse.getWeight();
			}
		}
		
		//apply squashing function to tmpPotential
		potential = squash(tmpPotential);
	}
	
	/*
	 * Squashing function method
	 */
	private double squash(double tmpPotential)
	{		
		return gradient*tmpPotential;
	}
	
	/*
	 * Boosting methods
	 */
	public void boost(double boost_value)
	{
		//update synapses by boost_value
		System.out.println("Outcome node "+nodeName+" boosting by "+boost_value);
		double delta_sw = calculateDeltaSW(boost_value);
		System.out.println("Delta_sw = "+delta_sw);
		updateWeights(delta_sw);
	}
	
	private double calculateDeltaSW(double boost_value)
	{
		//divide boost_value by the number of synapses with preNode=on
		int count = 0;
		Iterator<Synapse> synapses_it = synapses.iterator();
		while(synapses_it.hasNext())
		{
			Synapse nextSynapse = (Synapse)synapses_it.next();
			if(nextSynapse.getPreNode().active) //check if preNode is active
			{
				count++;
			}
		}
		System.out.println("no. of active synapses = "+count);
		return boost_value/count;
	}
	
	private void updateWeights(double update_value)
	{
		Iterator<Synapse> synapses_it = synapses.iterator();
		while(synapses_it.hasNext())
		{
			Synapse nextSynapse = (Synapse)synapses_it.next();
			if(nextSynapse.getPreNode().active) //check if preNode is active
			{
				double weight = nextSynapse.getWeight();
				double weight_prime = weight+update_value;
				nextSynapse.setWeight(weight_prime);
			}
		}
	}
	
	/*
	 * Setter methods
	 */
	public void initialiseGradient(double gradient)
	{
		this.gradient = gradient;
	}
	
	public void setGradient(double gradient)
	{
		this.gradient = gradient;
		calculatePotential();
	}
	
	public void setPotential(double potential)
	{
		this.potential = potential;
	}
	
	/*
	 * Getter methods
	 */
	public double getPotential()
	{
		return potential;
	}
}