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Code Issues Releases Wiki Activity

Replacing the termination logic to reduce run-times with marginal effect on quality.

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safraeli 2019-05-19 13:33:11 +03:00
parent 7d7efe40fb
commit 4b88ac2028
1 changed files with 27 additions and 13 deletions
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40
jsprit-core/src/main/java/com/graphhopper/jsprit/core/algorithm/termination/IterationWithoutImprovementTermination.java
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@ -48,6 +48,9 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
private List<Integer> unassignedCount;
private double bestCost = Double.MAX_VALUE;
private double terminationByCostPercentage = 0.0;
/**
* Constructs termination.
*
@ -55,6 +58,7 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
*/
public IterationWithoutImprovementTermination(int noIterationsWithoutImprovement) {
this.noIterationWithoutImprovement = noIterationsWithoutImprovement;
this.terminationByCostPercentage = 0.1; // TODO: Fetch it from configuration
costs = new ArrayList<>();
unassignedCount = new ArrayList<>();
log.debug("initialise " + this);
@ -67,22 +71,32 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
@Override
public boolean isPrematureBreak(SearchStrategy.DiscoveredSolution discoveredSolution) {
VehicleRoutingProblemSolution sol = discoveredSolution.getSolution();
if(this.terminationByCostPercentage == 0.0){
// The original logic that is counting the number of iterations without any change
if (discoveredSolution.isAccepted())
iterationsWithoutImprovement = 0;
else
iterationsWithoutImprovement++;
return (iterationsWithoutImprovement > noIterationWithoutImprovement);
}else {
// The alternative logic that detects also very slow improvment
// On large tasks small improvments to the route may significantly increase the runtime
VehicleRoutingProblemSolution sol = discoveredSolution.getSolution();
double currentCost = sol.getCost();
bestCost = Math.min(currentCost, bestCost);
costs.add(bestCost);
double currentCost = sol.getCost();
bestCost = Math.min(currentCost, bestCost);
costs.add(bestCost);
int currentUnassigned = sol.getUnassignedJobs().size();
unassignedCount.add(currentUnassigned);
int currentUnassigned = sol.getUnassignedJobs().size();
unassignedCount.add(currentUnassigned);
int i = costs.size() - 1;
if (i < noIterationWithoutImprovement)
return false;
int i = costs.size() - 1;
if (i < noIterationWithoutImprovement)
return false;
double progressPercentTerminationCondition = 0.1; // TODO: Move to configuration
boolean unassignedEqual = (currentUnassigned == unassignedCount.get(i-noIterationWithoutImprovement));
boolean progressTooSlow = (100 * Math.abs(currentCost - costs.get(i - noIterationWithoutImprovement))) / currentCost < progressPercentTerminationCondition;
return (unassignedEqual && progressTooSlow);
boolean unassignedEqual = (currentUnassigned == unassignedCount.get(i - noIterationWithoutImprovement));
boolean progressTooSlow = (100 * Math.abs(currentCost - costs.get(i - noIterationWithoutImprovement))) / currentCost < terminationByCostPercentage;
return (unassignedEqual && progressTooSlow);
}
}
}