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document core.algorithm.termination.VariationCoefficientTermination

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oblonski 2014-08-14 00:42:48 +02:00
parent ad39bea373
commit ec4a899938
1 changed files with 31 additions and 36 deletions
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67
jsprit-core/src/main/java/jsprit/core/algorithm/termination/VariationCoefficientTermination.java
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@ -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> * <p>Note, that this must be registered as AlgorithmListener <br>
* <code>algorithm.getAlgorithmListeners().addListener(this);</code> * It will be activated by:<br>
*
* <code>algorithm.setPrematureAlgorithmTermination(this);</code><br>
* <code>algorithm.addListener(this);</code>
*
* *
* * @author stefan schroeder
* @author stefan
* *
*/ */
public class VariationCoefficientTermination implements PrematureAlgorithmTermination, IterationStartsListener, AlgorithmStartsListener, IterationEndsListener{ public class VariationCoefficientTermination implements PrematureAlgorithmTermination, IterationStartsListener, AlgorithmStartsListener, IterationEndsListener{
private static Logger logger = LogManager.getLogger(VariationCoefficientTermination.class); 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 int currentIteration;
private double[] solutionValues; private double[] solutionValues;
private VehicleRoutingProblemSolution lastAccepted = null; private VehicleRoutingProblemSolution lastAccepted = null;
/** /**
* Breaks algorithm prematurely based on variationCoefficient. * Constructs termination.
* *
* <p>Note that this must be registered in algorithm<br> * @param noIterations size of the sample, i.e. number previous solutions values to take into account. If for example
* <code>algorithm.getAlgorithmListeners().addListener(this);</code> * 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
* @author stefan * is smaller than the specified threshold, the algorithm terminates.
* */
*/ public VariationCoefficientTermination(int noIterations, double variationCoefficientThreshold) {
public VariationCoefficientTermination(int nuOfIterations, double variationCoefficientThreshold) {
super(); super();
this.nuOfIterations = nuOfIterations; this.noIterations = noIterations;
this.variationCoefficientThreshold = variationCoefficientThreshold; this.variationCoefficientThreshold = variationCoefficientThreshold;
solutionValues = new double[nuOfIterations]; solutionValues = new double[noIterations];
logger.info("initialise " + this); logger.info("initialise " + this);
} }
@Override @Override
public String toString() { public String toString() {
return "[name=VariationCoefficientBreaker][variationCoefficientThreshold="+variationCoefficientThreshold+"][iterations="+nuOfIterations+"]"; return "[name=VariationCoefficientBreaker][variationCoefficientThreshold="+variationCoefficientThreshold+"][iterations="+ noIterations +"]";
} }
@Override @Override
public boolean isPrematureBreak(DiscoveredSolution discoveredSolution) { public boolean isPrematureBreak(DiscoveredSolution discoveredSolution) {
if(discoveredSolution.isAccepted()){ if(discoveredSolution.isAccepted()){
lastAccepted = discoveredSolution.getSolution(); lastAccepted = discoveredSolution.getSolution();
solutionValues[currentIteration]=discoveredSolution.getSolution().getCost(); solutionValues[currentIteration] = discoveredSolution.getSolution().getCost();
} }
else{ else{
if(lastAccepted != null){ 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) { if(currentIteration == (noIterations - 1)){
// logger.info(lastAccepted.getCost());
// logger.info("inArr,"+(currentIteration)+","+solutionValues[currentIteration]);
}
if(currentIteration == (nuOfIterations-1)){
double mean = StatUtils.mean(solutionValues); double mean = StatUtils.mean(solutionValues);
double stdDev = new StandardDeviation(true).evaluate(solutionValues, mean); double stdDev = new StandardDeviation(true).evaluate(solutionValues, mean);
double variationCoefficient = stdDev/mean; double variationCoefficient = stdDev / mean;
// logger.info("[mean="+mean+"][stdDev="+stdDev+"][variationCoefficient="+variationCoefficient+"]");
if(variationCoefficient < variationCoefficientThreshold){ if(variationCoefficient < variationCoefficientThreshold){
return true; return true;
} }
@ -108,7 +105,7 @@ public class VariationCoefficientTermination implements PrematureAlgorithmTermin
} }
private void reset(){ private void reset(){
currentIteration=0; currentIteration = 0;
} }
@Override @Override
@ -118,7 +115,7 @@ public class VariationCoefficientTermination implements PrematureAlgorithmTermin
@Override @Override
public void informIterationEnds(int i, VehicleRoutingProblem problem, Collection<VehicleRoutingProblemSolution> solutions) { public void informIterationEnds(int i, VehicleRoutingProblem problem, Collection<VehicleRoutingProblemSolution> solutions) {
if(currentIteration == (nuOfIterations-1)){ if(currentIteration == (noIterations - 1)){
reset(); reset();
} }
else{ else{
@ -131,6 +128,4 @@ public class VariationCoefficientTermination implements PrematureAlgorithmTermin
if(lastAccepted == null) lastAccepted = Solutions.bestOf(solutions); if(lastAccepted == null) lastAccepted = Solutions.bestOf(solutions);
} }
} }