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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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18
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 List<Integer> unassignedCount;
private double bestCost = Double.MAX_VALUE; private double bestCost = Double.MAX_VALUE;
private double terminationByCostPercentage = 0.0;
/** /**
* Constructs termination. * Constructs termination.
* *
@ -55,6 +58,7 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
*/ */
public IterationWithoutImprovementTermination(int noIterationsWithoutImprovement) { public IterationWithoutImprovementTermination(int noIterationsWithoutImprovement) {
this.noIterationWithoutImprovement = noIterationsWithoutImprovement; this.noIterationWithoutImprovement = noIterationsWithoutImprovement;
this.terminationByCostPercentage = 0.1; // TODO: Fetch it from configuration
costs = new ArrayList<>(); costs = new ArrayList<>();
unassignedCount = new ArrayList<>(); unassignedCount = new ArrayList<>();
log.debug("initialise " + this); log.debug("initialise " + this);
@ -67,6 +71,16 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
@Override @Override
public boolean isPrematureBreak(SearchStrategy.DiscoveredSolution discoveredSolution) { public boolean isPrematureBreak(SearchStrategy.DiscoveredSolution discoveredSolution) {
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(); VehicleRoutingProblemSolution sol = discoveredSolution.getSolution();
double currentCost = sol.getCost(); double currentCost = sol.getCost();
@ -80,9 +94,9 @@ public class IterationWithoutImprovementTermination implements PrematureAlgorith
if (i < noIterationWithoutImprovement) if (i < noIterationWithoutImprovement)
return false; return false;
double progressPercentTerminationCondition = 0.1; // TODO: Move to configuration
boolean unassignedEqual = (currentUnassigned == unassignedCount.get(i - noIterationWithoutImprovement)); boolean unassignedEqual = (currentUnassigned == unassignedCount.get(i - noIterationWithoutImprovement));
boolean progressTooSlow = (100 * Math.abs(currentCost - costs.get(i - noIterationWithoutImprovement))) / currentCost < progressPercentTerminationCondition; boolean progressTooSlow = (100 * Math.abs(currentCost - costs.get(i - noIterationWithoutImprovement))) / currentCost < terminationByCostPercentage;
return (unassignedEqual && progressTooSlow); return (unassignedEqual && progressTooSlow);
} }
} }
}