Examples with EstimateEvaluator org.neo4j.graphalgo.EstimateEvaluator used on opensource projects

Example 1 with EstimateEvaluator

use of org.neo4j.graphalgo.EstimateEvaluator in project neo4j-documentation by neo4j.

the class PathFindingDocTest method astarExample.

@SuppressWarnings("unused")
@Test
public void astarExample() {
    // START SNIPPET: astarUsage
    Node nodeA = createNode("name", "A", "x", 0d, "y", 0d);
    Node nodeB = createNode("name", "B", "x", 7d, "y", 0d);
    Node nodeC = createNode("name", "C", "x", 2d, "y", 1d);
    Relationship relAB = createRelationship(nodeA, nodeC, "length", 2d);
    Relationship relBC = createRelationship(nodeC, nodeB, "length", 3d);
    Relationship relAC = createRelationship(nodeA, nodeB, "length", 10d);
    EstimateEvaluator<Double> estimateEvaluator = new EstimateEvaluator<Double>() {

        @Override
        public Double getCost(final Node node, final Node goal) {
            double dx = (Double) node.getProperty("x") - (Double) goal.getProperty("x");
            double dy = (Double) node.getProperty("y") - (Double) goal.getProperty("y");
            double result = Math.sqrt(Math.pow(dx, 2) + Math.pow(dy, 2));
            return result;
        }
    };
    PathFinder<WeightedPath> astar = GraphAlgoFactory.aStar(PathExpanders.allTypesAndDirections(), CommonEvaluators.doubleCostEvaluator("length"), estimateEvaluator);
    WeightedPath path = astar.findSinglePath(nodeA, nodeB);
// END SNIPPET: astarUsage
}

Example 2 with EstimateEvaluator

use of org.neo4j.graphalgo.EstimateEvaluator in project graphdb by neo4j-attic.

the class PathFindingExamplesTest method astarExample.

@Test
public void astarExample() {
    // START SNIPPET: astarUsage
    Node nodeA = createNode("name", "A", "x", 0d, "y", 0d);
    Node nodeB = createNode("name", "B", "x", 7d, "y", 0d);
    Node nodeC = createNode("name", "C", "x", 2d, "y", 1d);
    Relationship relAB = createRelationship(nodeA, nodeC, "length", 2d);
    Relationship relBC = createRelationship(nodeC, nodeB, "length", 3d);
    Relationship relAC = createRelationship(nodeA, nodeB, "length", 10d);
    EstimateEvaluator<Double> estimateEvaluator = new EstimateEvaluator<Double>() {

        public Double getCost(final Node node, final Node goal) {
            double dx = (Double) node.getProperty("x") - (Double) goal.getProperty("x");
            double dy = (Double) node.getProperty("y") - (Double) goal.getProperty("y");
            double result = Math.sqrt(Math.pow(dx, 2) + Math.pow(dy, 2));
            return result;
        }
    };
    PathFinder<WeightedPath> astar = GraphAlgoFactory.aStar(Traversal.expanderForAllTypes(), CommonEvaluators.doubleCostEvaluator("length"), estimateEvaluator);
    WeightedPath path = astar.findSinglePath(nodeA, nodeB);
    // END SNIPPET: astarUsage
    System.out.println(path.weight());
}

Example 3 with EstimateEvaluator

use of org.neo4j.graphalgo.EstimateEvaluator in project neo4j by neo4j.

the class TestAStar method betterTentativePath.

@Test
void betterTentativePath() {
    // GIVEN
    try (Transaction transaction = graphDb.beginTx()) {
        EstimateEvaluator<Double> estimator = (node, goal) -> (Double) node.getProperty("estimate");
        var context = new BasicEvaluationContext(transaction, graphDb);
        PathFinder<WeightedPath> finder = aStar(context, allTypesAndDirections(), doubleCostEvaluator("weight", 0d), estimator);
        final Node node1 = graph.makeNode(transaction, "1", "estimate", 0.003d);
        final Node node2 = graph.makeNode(transaction, "2", "estimate", 0.002d);
        final Node node3 = graph.makeNode(transaction, "3", "estimate", 0.001d);
        final Node node4 = graph.makeNode(transaction, "4", "estimate", 0d);
        graph.makeEdge(transaction, "1", "3", "weight", 0.253d);
        graph.makeEdge(transaction, "1", "2", "weight", 0.018d);
        graph.makeEdge(transaction, "2", "4", "weight", 0.210d);
        graph.makeEdge(transaction, "2", "3", "weight", 0.180d);
        graph.makeEdge(transaction, "2", "3", "weight", 0.024d);
        graph.makeEdge(transaction, "3", "4", "weight", 0.135d);
        graph.makeEdge(transaction, "3", "4", "weight", 0.013d);
        // WHEN
        WeightedPath best14 = finder.findSinglePath(node1, node4);
        // THEN
        assertPath(best14, node1, node2, node3, node4);
        transaction.commit();
    }
}