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October 12, 2022 20:59
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This is a demo file to show an issue in or-tools I am facing.
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| import com.google.ortools.Loader; | |
| import com.google.ortools.constraintsolver.Assignment; | |
| import com.google.ortools.constraintsolver.FirstSolutionStrategy; | |
| import com.google.ortools.constraintsolver.RoutingDimension; | |
| import com.google.ortools.constraintsolver.RoutingIndexManager; | |
| import com.google.ortools.constraintsolver.RoutingModel; | |
| import com.google.ortools.constraintsolver.RoutingSearchParameters; | |
| import com.google.ortools.constraintsolver.main; | |
| public class Testortools { | |
| public static void main(String[] args) { | |
| Loader.loadNativeLibraries(); | |
| int deliveryCount = 5; | |
| int vehicleCount = 1; | |
| /* index zero is our start warehouse, index one is end warehouse */ | |
| /* deliveries start from index 2*/ | |
| long[] deliveryWeights = new long[] { 0, 0, 50, 30, 30 }; | |
| long[] penalties = new long[] { 1, 1, 100, 5, 5 }; | |
| long[] vehicleWeights = new long[] { 75 }; | |
| long[][] durations = new long[][] { { 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0 }, | |
| { 0, 0, 0, 0, 0 } }; | |
| int[] starts = new int[] { 0 }; | |
| int[] ends = new int[] { 1 }; | |
| RoutingIndexManager manager = new RoutingIndexManager(deliveryCount, vehicleCount, starts, ends); | |
| RoutingModel routing = new RoutingModel(manager); | |
| /* Time Dimension */ | |
| int timeCallback = routing.registerTransitCallback((fromIndex, toIndex) -> { | |
| int from = manager.indexToNode(fromIndex); | |
| int to = manager.indexToNode(toIndex); | |
| return durations[from][to]; | |
| }); | |
| routing.setArcCostEvaluatorOfAllVehicles(timeCallback); | |
| routing.addDimension(timeCallback, Long.MAX_VALUE, Long.MAX_VALUE, false, | |
| "Time"); | |
| /* Weight dimension */ | |
| int weightCallback = routing.registerUnaryTransitCallback(index -> { | |
| int node = manager.indexToNode(index); | |
| return deliveryWeights[node]; | |
| }); | |
| for (int i = 0; i < vehicleCount; i++) | |
| routing.addDimensionWithVehicleCapacity(weightCallback, 0, vehicleWeights, true, "Count"); | |
| /* Dropping Constraints */ | |
| for (int i = 2; i < deliveryCount; i++) { | |
| long penalty = penalties[i]; | |
| routing.addDisjunction(new long[] { manager.nodeToIndex(i) }, penalty * 1000); | |
| } | |
| /* Search parameters & Solve */ | |
| RoutingSearchParameters searchParameters = main.defaultRoutingSearchParameters().toBuilder() | |
| .setFirstSolutionStrategy(FirstSolutionStrategy.Value.PATH_CHEAPEST_ARC) | |
| .build(); | |
| routing.closeModelWithParameters(searchParameters); | |
| Assignment solution = routing.solveWithParameters(searchParameters); | |
| /* No solution? */ | |
| if (solution == null) { | |
| System.out.println("No solution"); | |
| return; | |
| } | |
| System.out.println("Objective value " + solution.objectiveValue()); | |
| /* See dropped nodes */ | |
| RoutingDimension count = routing.getMutableDimension("Count"); | |
| for (int i = 0; i < routing.size(); i++) { | |
| if (routing.isStart(i) || routing.isEnd(i)) { | |
| continue; | |
| } | |
| if (solution.value(routing.nextVar(i)) == i) | |
| System.out.println("Dropped node " + manager.indexToNode(i)); | |
| } | |
| /* See routes */ | |
| for (int i = 0; i < vehicleCount; i++) { | |
| System.out.println("Vehicle " + i); | |
| long index = routing.start(i); | |
| while (index != routing.end(i)) { | |
| System.out.println( | |
| "Index " + manager.indexToNode(index) + ", weight " | |
| + solution.value(count.cumulVar(index))); | |
| index = solution.value(routing.nextVar(index)); | |
| } | |
| } | |
| } | |
| } |
The for loop in line 48 would lead to an error if vehicleCount was more than 1.
Thanks @abeham , that's actually hard coded, but the issue is with solver probably. Do you see any other issues with code?
No, not really.
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After running, logs are:
Objective value 100000
Dropped order 2
Vehicle 0
Index 0, weight 0
Index 4, weight 0
Index 3, weight 30
Here, index 0 is start warehouse, 1 is end warehouse.
Weights are {0,0,50,30,30}
Penalties {1,1,100,5,5}
Index 0 1 (2 3 4)