Examples with AStar com.graphhopper.routing.AStar used on opensource projects

Example 1 with AStar

use of com.graphhopper.routing.AStar in project graphhopper by graphhopper.

the class LMRoutingAlgorithmFactory method createAlgo.

@Override
public RoutingAlgorithm createAlgo(Graph g, Weighting w, AlgorithmOptions opts) {
    if (!lms.isInitialized())
        throw new IllegalStateException("Initialize landmark storage before creating algorithms");
    int activeLM = Math.max(1, opts.getHints().getInt(Parameters.Landmark.ACTIVE_COUNT, defaultActiveLandmarks));
    final String algoStr = opts.getAlgorithm();
    final Weighting weighting = g.wrapWeighting(w);
    if (ASTAR.equalsIgnoreCase(algoStr)) {
        double epsilon = opts.getHints().getDouble(Parameters.Algorithms.AStar.EPSILON, 1);
        AStar algo = new AStar(g, weighting, opts.getTraversalMode());
        algo.setApproximation(getApproximator(g, activeLM, epsilon));
        algo.setMaxVisitedNodes(opts.getMaxVisitedNodes());
        return algo;
    } else if (ASTAR_BI.equalsIgnoreCase(algoStr) || Helper.isEmpty(algoStr)) {
        double epsilon = opts.getHints().getDouble(Parameters.Algorithms.AStarBi.EPSILON, 1);
        AStarBidirection algo = new AStarBidirection(g, weighting, opts.getTraversalMode());
        algo.setApproximation(getApproximator(g, activeLM, epsilon));
        algo.setMaxVisitedNodes(opts.getMaxVisitedNodes());
        return algo;
    } else if (ALT_ROUTE.equalsIgnoreCase(algoStr)) {
        double epsilon = opts.getHints().getDouble(Parameters.Algorithms.AStarBi.EPSILON, 1);
        AlternativeRoute algo = new AlternativeRoute(g, weighting, opts.getTraversalMode());
        algo.setMaxPaths(opts.getHints().getInt(MAX_PATHS, 2));
        algo.setMaxWeightFactor(opts.getHints().getDouble(MAX_WEIGHT, 1.4));
        algo.setMaxShareFactor(opts.getHints().getDouble(MAX_SHARE, 0.6));
        algo.setMinPlateauFactor(opts.getHints().getDouble("alternative_route.min_plateau_factor", 0.2));
        algo.setApproximation(getApproximator(g, activeLM, epsilon));
        // landmark algorithm follows good compromise between fast response and exploring 'interesting' paths so we
        // can decrease this exploration factor further (1->dijkstra, 0.8->bidir. A*)
        algo.setMaxExplorationFactor(0.6);
        algo.setMaxVisitedNodes(opts.getMaxVisitedNodes());
        return algo;
    } else {
        throw new IllegalArgumentException("Landmarks algorithm only supports algorithm=" + ASTAR + "," + ASTAR_BI + " or " + ALT_ROUTE + ", but got: " + algoStr);
    }
}

Example 2 with AStar

use of com.graphhopper.routing.AStar in project graphhopper by graphhopper.

the class PrepareLandmarksTest method testLandmarkStorageAndRouting.

@Test
public void testLandmarkStorageAndRouting() {
    // create graph with lat,lon
    // 0  1  2  ...
    // 15 16 17 ...
    Random rand = new Random(0);
    int width = 15, height = 15;
    DecimalEncodedValue avSpeedEnc = encoder.getAverageSpeedEnc();
    BooleanEncodedValue accessEnc = encoder.getAccessEnc();
    for (int hIndex = 0; hIndex < height; hIndex++) {
        for (int wIndex = 0; wIndex < width; wIndex++) {
            int node = wIndex + hIndex * width;
            // do not connect first with last column!
            double speed = 20 + rand.nextDouble() * 30;
            if (wIndex + 1 < width)
                graph.edge(node, node + 1).set(accessEnc, true, true).set(avSpeedEnc, speed);
            // avoid dead ends
            if (hIndex + 1 < height)
                graph.edge(node, node + width).set(accessEnc, true, true).set(avSpeedEnc, speed);
            updateDistancesFor(graph, node, -hIndex / 50.0, wIndex / 50.0);
        }
    }
    Directory dir = new RAMDirectory();
    LocationIndexTree index = new LocationIndexTree(graph, dir);
    index.prepareIndex();
    int lm = 5, activeLM = 2;
    Weighting weighting = new FastestWeighting(encoder);
    LMConfig lmConfig = new LMConfig("car", weighting);
    LandmarkStorage store = new LandmarkStorage(graph, dir, lmConfig, lm);
    store.setMinimumNodes(2);
    store.createLandmarks();
    // landmarks should be the 4 corners of the grid:
    int[] intList = store.getLandmarks(1);
    Arrays.sort(intList);
    assertEquals("[0, 14, 70, 182, 224]", Arrays.toString(intList));
    // two landmarks: one for subnetwork 0 (all empty) and one for subnetwork 1
    assertEquals(2, store.getSubnetworksWithLandmarks());
    assertEquals(0, store.getFromWeight(0, 224));
    double factor = store.getFactor();
    assertEquals(4671, Math.round(store.getFromWeight(0, 47) * factor));
    assertEquals(3640, Math.round(store.getFromWeight(0, 52) * factor));
    long weight1_224 = store.getFromWeight(1, 224);
    assertEquals(5525, Math.round(weight1_224 * factor));
    long weight1_47 = store.getFromWeight(1, 47);
    assertEquals(921, Math.round(weight1_47 * factor));
    // grid is symmetric
    assertEquals(weight1_224, store.getToWeight(1, 224));
    assertEquals(weight1_47, store.getToWeight(1, 47));
    // prefer the landmarks before and behind the goal
    int[] activeLandmarkIndices = new int[activeLM];
    Arrays.fill(activeLandmarkIndices, -1);
    store.chooseActiveLandmarks(27, 47, activeLandmarkIndices, false);
    List<Integer> list = new ArrayList<>();
    for (int idx : activeLandmarkIndices) {
        list.add(store.getLandmarks(1)[idx]);
    }
    // TODO should better select 0 and 224?
    assertEquals(Arrays.asList(224, 70), list);
    PrepareLandmarks prepare = new PrepareLandmarks(new RAMDirectory(), graph, lmConfig, 4);
    prepare.setMinimumNodes(2);
    prepare.doWork();
    LandmarkStorage lms = prepare.getLandmarkStorage();
    AStar expectedAlgo = new AStar(graph, weighting, tm);
    Path expectedPath = expectedAlgo.calcPath(41, 183);
    PMap hints = new PMap().putObject(Parameters.Landmark.ACTIVE_COUNT, 2);
    // landmarks with A*
    RoutingAlgorithm oneDirAlgoWithLandmarks = new LMRoutingAlgorithmFactory(lms).createAlgo(graph, weighting, new AlgorithmOptions().setAlgorithm(ASTAR).setTraversalMode(tm).setHints(hints));
    Path path = oneDirAlgoWithLandmarks.calcPath(41, 183);
    assertEquals(expectedPath.getWeight(), path.getWeight(), .1);
    assertEquals(expectedPath.calcNodes(), path.calcNodes());
    assertEquals(expectedAlgo.getVisitedNodes() - 135, oneDirAlgoWithLandmarks.getVisitedNodes());
    // landmarks with bidir A*
    RoutingAlgorithm biDirAlgoWithLandmarks = new LMRoutingAlgorithmFactory(lms).createAlgo(graph, weighting, new AlgorithmOptions().setAlgorithm(ASTAR_BI).setTraversalMode(tm).setHints(hints));
    path = biDirAlgoWithLandmarks.calcPath(41, 183);
    assertEquals(expectedPath.getWeight(), path.getWeight(), .1);
    assertEquals(expectedPath.calcNodes(), path.calcNodes());
    assertEquals(expectedAlgo.getVisitedNodes() - 162, biDirAlgoWithLandmarks.getVisitedNodes());
    // landmarks with A* and a QueryGraph. We expect slightly less optimal as two more cycles needs to be traversed
    // due to the two more virtual nodes but this should not harm in practise
    Snap fromSnap = index.findClosest(-0.0401, 0.2201, EdgeFilter.ALL_EDGES);
    Snap toSnap = index.findClosest(-0.2401, 0.0601, EdgeFilter.ALL_EDGES);
    QueryGraph qGraph = QueryGraph.create(graph, fromSnap, toSnap);
    RoutingAlgorithm qGraphOneDirAlgo = new LMRoutingAlgorithmFactory(lms).createAlgo(qGraph, weighting, new AlgorithmOptions().setAlgorithm(ASTAR).setTraversalMode(tm).setHints(hints));
    path = qGraphOneDirAlgo.calcPath(fromSnap.getClosestNode(), toSnap.getClosestNode());
    expectedAlgo = new AStar(qGraph, weighting, tm);
    expectedPath = expectedAlgo.calcPath(fromSnap.getClosestNode(), toSnap.getClosestNode());
    assertEquals(expectedPath.getWeight(), path.getWeight(), .1);
    assertEquals(expectedPath.calcNodes(), path.calcNodes());
    assertEquals(expectedAlgo.getVisitedNodes() - 135, qGraphOneDirAlgo.getVisitedNodes());
}