dvrp: skip computing sparse TT matrix when not needed

When max duration and distance are set to zero, there is no point in computing te sparce matrix,
which may be very time consuming for very large networks.

contribs/dvrp/src/main/java/org/matsim/contrib/zone/skims/FreeSpeedTravelTimeMatrix.java

@@ -33,7 +33,7 @@
  */
 public class FreeSpeedTravelTimeMatrix implements TravelTimeMatrix {
 	public static FreeSpeedTravelTimeMatrix createFreeSpeedMatrix(Network dvrpNetwork, DvrpTravelTimeMatrixParams params, int numberOfThreads,
-			double qSimTimeStepSize) {
+		double qSimTimeStepSize) {
 		return new FreeSpeedTravelTimeMatrix(dvrpNetwork, params, numberOfThreads, new QSimFreeSpeedTravelTime(qSimTimeStepSize));
 	}
 
@@ -48,17 +48,19 @@ public FreeSpeedTravelTimeMatrix(Network dvrpNetwork, DvrpTravelTimeMatrixParams
 		var routingParams = new TravelTimeMatrices.RoutingParams(dvrpNetwork, travelTime, travelDisutility, numberOfThreads);
 		freeSpeedTravelTimeMatrix = TravelTimeMatrices.calculateTravelTimeMatrix(routingParams, centralNodes, 0);
 		freeSpeedTravelTimeSparseMatrix = TravelTimeMatrices.calculateTravelTimeSparseMatrix(routingParams, params.maxNeighborDistance,
-				params.maxNeighborTravelTime, 0);
+			params.maxNeighborTravelTime, 0).orElse(null);
 	}
 
 	@Override
 	public int getTravelTime(Node fromNode, Node toNode, double departureTime) {
 		if (fromNode == toNode) {
 			return 0;
 		}
-		int time = freeSpeedTravelTimeSparseMatrix.get(fromNode, toNode);
-		if (time >= 0) {// value is present
-			return time;
+		if (freeSpeedTravelTimeSparseMatrix != null) {
+			int time = freeSpeedTravelTimeSparseMatrix.get(fromNode, toNode);
+			if (time >= 0) {// value is present
+				return time;
+			}
 		}
 		return freeSpeedTravelTimeMatrix.get(gridSystem.getZone(fromNode), gridSystem.getZone(toNode));
 	}

contribs/dvrp/src/main/java/org/matsim/contrib/zone/skims/TravelTimeMatrices.java

@@ -23,6 +23,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.stream.IntStream;
 
 import org.matsim.api.core.v01.network.Network;
@@ -56,7 +57,7 @@ public static Matrix calculateTravelTimeMatrix(RoutingParams params, Map<Zone, N
 	}
 
 	private static void computeForDepartureZone(Zone fromZone, Map<Zone, Node> centralNodes, double departureTime, Matrix travelTimeMatrix,
-			LeastCostPathTree lcpTree) {
+		LeastCostPathTree lcpTree) {
 		Node fromNode = centralNodes.get(fromZone);
 		lcpTree.calculate(fromNode.getId().index(), departureTime, null, null);
 
@@ -65,26 +66,31 @@ private static void computeForDepartureZone(Zone fromZone, Map<Zone, Node> centr
 			int nodeIndex = toNode.getId().index();
 			OptionalTime currOptionalTime = lcpTree.getTime(nodeIndex);
 			double currTime = currOptionalTime.orElseThrow(() -> new RuntimeException(
-					"Undefined Time. Reason could be that the dvrp network is not fully connected. Please check and/or clean."));
+				"Undefined Time. Reason could be that the dvrp network is not fully connected. Please check and/or clean."));
 			double tt = currTime - departureTime;
 			travelTimeMatrix.set(fromZone, toZone, tt);
 		}
 	}
 
-	public static SparseMatrix calculateTravelTimeSparseMatrix(RoutingParams params, double maxDistance, double maxTravelTime, double departureTime) {
+	public static Optional<SparseMatrix> calculateTravelTimeSparseMatrix(RoutingParams params, double maxDistance, double maxTravelTime,
+		double departureTime) {
 		SparseMatrix travelTimeMatrix = new SparseMatrix();
+		if (maxDistance == 0 && maxTravelTime == 0) {
+			return Optional.empty();
+		}
+
 		var nodes = params.routingNetwork.getNodes().values();
 		var counter = "DVRP free-speed TT sparse matrix: node ";
 		Calculation<Node> calculation = (lcpTree, n) -> computeForDepartureNode(n, nodes, departureTime, travelTimeMatrix, lcpTree, maxDistance,
-				maxTravelTime);
+			maxTravelTime);
 		calculate(params, nodes, calculation, counter);
-		return travelTimeMatrix;
+		return Optional.of(travelTimeMatrix);
 	}
 
 	private static void computeForDepartureNode(Node fromNode, Collection<? extends Node> nodes, double departureTime, SparseMatrix sparseMatrix,
-			LeastCostPathTree lcpTree, double maxDistance, double maxTravelTime) {
+		LeastCostPathTree lcpTree, double maxDistance, double maxTravelTime) {
 		lcpTree.calculate(fromNode.getId().index(), departureTime, null, null,
-				(nodeIndex, arrivalTime, travelCost, distance, departTime) -> distance >= maxDistance && arrivalTime >= departTime + maxTravelTime);
+			(nodeIndex, arrivalTime, travelCost, distance, departTime) -> distance >= maxDistance && arrivalTime >= departTime + maxTravelTime);
 
 		List<NodeAndTime> neighborNodes = new ArrayList<>();
 		for (Node toNode : nodes) {
@@ -109,8 +115,8 @@ private interface Calculation<E> {
 
 	private static <E> void calculate(RoutingParams params, Collection<? extends E> elements, Calculation<E> calculation, String counterPrefix) {
 		var trees = IntStream.range(0, params.numberOfThreads)
-				.mapToObj(i -> new LeastCostPathTree(new SpeedyGraph(params.routingNetwork), params.travelTime, params.travelDisutility))
-				.toList();
+			.mapToObj(i -> new LeastCostPathTree(new SpeedyGraph(params.routingNetwork), params.travelTime, params.travelDisutility))
+			.toList();
 		var executorService = new ExecutorServiceWithResource<>(trees);
 		var counter = new Counter(counterPrefix, " / " + elements.size());
 

contribs/dvrp/src/test/java/org/matsim/contrib/zone/skims/TravelTimeMatricesTest.java

@@ -69,7 +69,7 @@ public void travelTimeSparseMatrix_maxDistance() {
 		NetworkUtils.createAndAddLink(network, Id.createLinkId("CA"), nodeC, nodeA, 600, 15, 80, 1);
 
 		double maxDistance = 300;// B->A->C and C->A->B are pruned by  the limit
-		var matrix = TravelTimeMatrices.calculateTravelTimeSparseMatrix(routingParams(network), maxDistance, 0, 0);
+		var matrix = TravelTimeMatrices.calculateTravelTimeSparseMatrix(routingParams(network), maxDistance, 0, 0).orElseThrow();
 
 		assertThat(matrix.get(nodeA, nodeA)).isEqualTo(0);
 		assertThat(matrix.get(nodeA, nodeB)).isEqualTo(10);
@@ -97,7 +97,7 @@ public void travelTimeSparseMatrix_maxTravelTime() {
 
 		// 20 s (max TT) corresponds to 300 m (max distance) in another test (see: travelTimeSparseMatrix_maxDistance())
 		double maxTravelTime = 20;// B->A->C and C->A->B are pruned by  the limit
-		var matrix = TravelTimeMatrices.calculateTravelTimeSparseMatrix(routingParams(network), 0, maxTravelTime, 0);
+		var matrix = TravelTimeMatrices.calculateTravelTimeSparseMatrix(routingParams(network), 0, maxTravelTime, 0).orElseThrow();
 
 		assertThat(matrix.get(nodeA, nodeA)).isEqualTo(0);
 		assertThat(matrix.get(nodeA, nodeB)).isEqualTo(10);