RandomizingTimeDistanceTravelDisutility.java

Go to the documentation of this file.

/* *********************************************************************** *
 * project: org.matsim.*
 * TravelTimeDistanceCostCalculator.java
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 * copyright       : (C) 2007 by the members listed in the COPYING,        *
 *                   LICENSE and WARRANTY file.                            *
 * email           : info at matsim dot org                                *
 *                                                                         *
 * *********************************************************************** *
 *                                                                         *
 *   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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *   See also COPYING, LICENSE and WARRANTY file                           *
 *                                                                         *
 * *********************************************************************** */

package org.matsim.core.router.costcalculators;

import org.matsim.api.core.v01.network.Link;
import org.matsim.api.core.v01.population.Person;
import org.matsim.core.gbl.MatsimRandom;
import org.matsim.core.router.util.TravelDisutility;
import org.matsim.core.router.util.TravelTime;
import org.matsim.vehicles.Vehicle;

import java.util.Random;

final class RandomizingTimeDistanceTravelDisutility implements TravelDisutility {

    private final TravelTime timeCalculator;
    private final double marginalCostOfTime;
    private final double marginalCostOfDistance;
    
    private final double normalization ;
    private final double sigma ;

    private final Random random;

    // "cache" of the random value
    private double logNormalRnd;
    private Person prevPerson;

    RandomizingTimeDistanceTravelDisutility(
            final TravelTime timeCalculator,
            final double marginalCostOfTime_s,
            final double marginalCostOfDistance_m,
            final double normalization,
            final double sigma) {
        this.timeCalculator = timeCalculator;
        this.marginalCostOfTime = marginalCostOfTime_s;
        this.marginalCostOfDistance = marginalCostOfDistance_m;
        this.normalization = normalization;
        this.sigma = sigma;
        this.random = sigma != 0 ? MatsimRandom.getLocalInstance() : null;
    }

    @Override
    public double getLinkTravelDisutility(final Link link, final double time, final Person person, final Vehicle vehicle) {
        // randomize if applicable:
        if ( sigma != 0. ) {
            if ( person==null ) {
                throw new RuntimeException("you cannot use the randomzing travel disutility without person.  If you need this without a person, set"
                        + " sigma to zero. If you are loading a scenario from a config, set the routingRandomness in the plansCalcRoute config group to zero.") ;
            }
            if ( person != prevPerson ) {
                prevPerson = person ;

                logNormalRnd = Math.exp( sigma * random.nextGaussian() ) ;
                logNormalRnd *= normalization ;
                // this should be a log-normal distribution with sigma as the "width" parameter.   Instead of figuring out the "location"
                // parameter mu, I rather just normalize (which should be the same, see next). kai, nov'13

                /* The argument is something like this:<ul> 
                 * <li> exp( mu + sigma * Z) with Z = Gaussian generates lognormal with mu and sigma.
                 * <li> The mean of this is exp( mu + sigma^2/2 ) .  
                 * <li> If we set mu=0, the expectation value is exp( sigma^2/2 ) .
                 * <li> So in order to set the expectation value to one (which is what we want), we need to divide by exp( sigma^2/2 ) .
                 * </ul>
                 * Should be tested. kai, jan'14 */
            }
            // do not use custom attributes in core??  but what would be a better solution here?? kai, mar'15
            // Is this actually used anywhere? As far as I can see, this is at least no used in this class... td, Oct'15
            person.getCustomAttributes().put("logNormalRnd", logNormalRnd ) ;
        } else {
            logNormalRnd = 1. ;
        }
        
        // end randomize
        
        double travelTime = this.timeCalculator.getLinkTravelTime(link, time, person, vehicle);
        return this.marginalCostOfTime * travelTime + logNormalRnd * this.marginalCostOfDistance * link.getLength();
    }

    @Override
    public double getLinkMinimumTravelDisutility(final Link link) {
        return (link.getLength() / link.getFreespeed()) * this.marginalCostOfTime + this.marginalCostOfDistance * link.getLength();
    }

}