trans/graphhopper-jsprit
1
0
Fork 0
mirror of https://github.com/graphhopper/jsprit.git synced 2020-01-24 07:45:05 +01:00
Code Issues Releases Wiki Activity

document core.algorithm.termination.VariationCoefficientTermination

Browse source
This commit is contained in:
oblonski 2014-08-14 00:42:48 +02:00
parent ad39bea373
commit ec4a899938
1 changed files with 31 additions and 36 deletions
Download patch file Download diff file Expand all files Collapse all files

67
jsprit-core/src/main/java/jsprit/core/algorithm/termination/VariationCoefficientTermination.java
View file

@ -33,73 +33,70 @@ import java.util.Collection;
/**
* Breaks algorithm prematurely based on variationCoefficient.
* Terminates algorithm prematurely based on variationCoefficient (http://en.wikipedia.org/wiki/Coefficient_of_variation).
*
* <p>Note that this must be registered in algorithm<br>
* <code>algorithm.getAlgorithmListeners().addListener(this);</code>
* <p>Note, that this must be registered as AlgorithmListener <br>
* It will be activated by:<br>
*
* <code>algorithm.setPrematureAlgorithmTermination(this);</code><br>
* <code>algorithm.addListener(this);</code>
*
*
*
* @author stefan
* @author stefan schroeder
*
*/
public class VariationCoefficientTermination implements PrematureAlgorithmTermination, IterationStartsListener, AlgorithmStartsListener, IterationEndsListener{
private static Logger logger = LogManager.getLogger(VariationCoefficientTermination.class);
private int nuOfIterations;
private final int noIterations;
private double variationCoefficientThreshold;
private final double variationCoefficientThreshold;
private int currentIteration;
private double[] solutionValues;
private VehicleRoutingProblemSolution lastAccepted = null;
/**
* Breaks algorithm prematurely based on variationCoefficient.
*
* <p>Note that this must be registered in algorithm<br>
* <code>algorithm.getAlgorithmListeners().addListener(this);</code>
*
*
* @author stefan
*
*/
public VariationCoefficientTermination(int nuOfIterations, double variationCoefficientThreshold) {
/**
* Constructs termination.
*
* @param noIterations size of the sample, i.e. number previous solutions values to take into account. If for example
* noIterations = 10 then every 10th iteration the variationCoefficient will be calculated with the
* last 10 solution values.
* @param variationCoefficientThreshold the threshold used to terminate the algorithm. If the calculated variationCoefficient
* is smaller than the specified threshold, the algorithm terminates.
*/
public VariationCoefficientTermination(int noIterations, double variationCoefficientThreshold) {
super();
this.nuOfIterations = nuOfIterations;
this.noIterations = noIterations;
this.variationCoefficientThreshold = variationCoefficientThreshold;
solutionValues = new double[nuOfIterations];
solutionValues = new double[noIterations];
logger.info("initialise " + this);
}
@Override
public String toString() {
return "[name=VariationCoefficientBreaker][variationCoefficientThreshold="+variationCoefficientThreshold+"][iterations="+nuOfIterations+"]";
return "[name=VariationCoefficientBreaker][variationCoefficientThreshold="+variationCoefficientThreshold+"][iterations="+ noIterations +"]";
}
@Override
public boolean isPrematureBreak(DiscoveredSolution discoveredSolution) {
if(discoveredSolution.isAccepted()){
lastAccepted = discoveredSolution.getSolution();
solutionValues[currentIteration]=discoveredSolution.getSolution().getCost();
solutionValues[currentIteration] = discoveredSolution.getSolution().getCost();
}
else{
if(lastAccepted != null){
solutionValues[currentIteration]=lastAccepted.getCost();
solutionValues[currentIteration] = lastAccepted.getCost();
}
else solutionValues[currentIteration]=Integer.MAX_VALUE;
else solutionValues[currentIteration] = Integer.MAX_VALUE;
}
if(lastAccepted !=null) {
// logger.info(lastAccepted.getCost());
// logger.info("inArr,"+(currentIteration)+","+solutionValues[currentIteration]);
}
if(currentIteration == (nuOfIterations-1)){
if(currentIteration == (noIterations - 1)){
double mean = StatUtils.mean(solutionValues);
double stdDev = new StandardDeviation(true).evaluate(solutionValues, mean);
double variationCoefficient = stdDev/mean;
// logger.info("[mean="+mean+"][stdDev="+stdDev+"][variationCoefficient="+variationCoefficient+"]");
double variationCoefficient = stdDev / mean;
if(variationCoefficient < variationCoefficientThreshold){
return true;
}
@ -108,7 +105,7 @@ public class VariationCoefficientTermination implements PrematureAlgorithmTermin
}
private void reset(){
currentIteration=0;
currentIteration = 0;
}
@Override
@ -118,7 +115,7 @@ public class VariationCoefficientTermination implements PrematureAlgorithmTermin
@Override
public void informIterationEnds(int i, VehicleRoutingProblem problem, Collection<VehicleRoutingProblemSolution> solutions) {
if(currentIteration == (nuOfIterations-1)){
if(currentIteration == (noIterations - 1)){
reset();
}
else{
@ -131,6 +128,4 @@ public class VariationCoefficientTermination implements PrematureAlgorithmTermin
if(lastAccepted == null) lastAccepted = Solutions.bestOf(solutions);
}
}