/** Test case for extracting paths */
@Test
public void testPath() {
graph.makeEdge("a", "b", "cost", (double) 1);
graph.makeEdge("b", "c", "cost", (double) 1);
graph.makeEdge("c", "d", "cost", (double) 1);
graph.makeEdge("d", "e", "cost", (double) 1);
graph.makeEdge("e", "f", "cost", (double) 1);
FloydWarshall<Double> floydWarshall =
new FloydWarshall<Double>(
0.0,
Double.MAX_VALUE,
Direction.OUTGOING,
CommonEvaluators.doubleCostEvaluator("cost"),
new org.neo4j.graphalgo.impl.util.DoubleAdder(),
new org.neo4j.graphalgo.impl.util.DoubleComparator(),
graph.getAllNodes(),
graph.getAllEdges());
List<Node> path = floydWarshall.getPath(graph.getNode("a"), graph.getNode("f"));
assertTrue(path.size() == 6);
assertTrue(path.get(0).equals(graph.getNode("a")));
assertTrue(path.get(1).equals(graph.getNode("b")));
assertTrue(path.get(2).equals(graph.getNode("c")));
assertTrue(path.get(3).equals(graph.getNode("d")));
assertTrue(path.get(4).equals(graph.getNode("e")));
assertTrue(path.get(5).equals(graph.getNode("f")));
}
@Test
public void canGetMultiplePathsInTriangleGraph() throws Exception {
Node nodeA = graph.makeNode("A");
Node nodeB = graph.makeNode("B");
Node nodeC = graph.makeNode("C");
Set<Relationship> expectedFirsts = new HashSet<Relationship>();
expectedFirsts.add(graph.makeEdge("A", "B", "length", 1d));
expectedFirsts.add(graph.makeEdge("A", "B", "length", 1d));
Relationship expectedSecond = graph.makeEdge("B", "C", "length", 2d);
graph.makeEdge("A", "C", "length", 5d);
Dijkstra algo =
new Dijkstra(
PathExpanders.allTypesAndDirections(), CommonEvaluators.doubleCostEvaluator("length"));
Iterator<WeightedPath> paths = algo.findAllPaths(nodeA, nodeC).iterator();
for (int i = 0; i < 2; i++) {
assertTrue("expected more paths", paths.hasNext());
Path path = paths.next();
assertPath(path, nodeA, nodeB, nodeC);
Iterator<Relationship> relationships = path.relationships().iterator();
assertTrue("found shorter path than expected", relationships.hasNext());
assertTrue(
"path contained unexpected relationship", expectedFirsts.remove(relationships.next()));
assertTrue("found shorter path than expected", relationships.hasNext());
assertEquals(expectedSecond, relationships.next());
assertFalse("found longer path than expected", relationships.hasNext());
}
assertFalse("expected at most two paths", paths.hasNext());
}
private PathFinder<? extends Path> getAlgorithm(
String algorithm, RelationshipExpander expander, int maxDepth) {
if (algorithm.equals("shortestPath")) {
return GraphAlgoFactory.shortestPath(expander, maxDepth);
} else if (algorithm.equals("allSimplePaths")) {
return GraphAlgoFactory.allSimplePaths(expander, maxDepth);
} else if (algorithm.equals("allPaths")) {
return GraphAlgoFactory.allPaths(expander, maxDepth);
} else if (algorithm.equals("dijkstra")) {
String costProperty = (String) map.get("cost_property");
Number defaultCost = (Number) map.get("default_cost");
CostEvaluator<Double> costEvaluator =
defaultCost == null
? CommonEvaluators.doubleCostEvaluator(costProperty)
: CommonEvaluators.doubleCostEvaluator(costProperty, defaultCost.doubleValue());
representationCreator = WEIGHTED_PATH_REPRESENTATION_CREATOR;
return GraphAlgoFactory.dijkstra(expander, costEvaluator);
}
throw new RuntimeException("Failed to find matching algorithm");
}
@Test
public void canGetPathsInTriangleGraph() throws Exception {
Node nodeA = graph.makeNode("A");
Node nodeB = graph.makeNode("B");
Node nodeC = graph.makeNode("C");
graph.makeEdge("A", "B", "length", 2d);
graph.makeEdge("B", "C", "length", 3d);
graph.makeEdge("A", "C", "length", 10d);
Dijkstra algo =
new Dijkstra(
PathExpanders.allTypesAndDirections(), CommonEvaluators.doubleCostEvaluator("length"));
Iterator<WeightedPath> paths = algo.findAllPaths(nodeA, nodeC).iterator();
assertTrue("expected at least one path", paths.hasNext());
assertPath(paths.next(), nodeA, nodeB, nodeC);
assertFalse("expected at most one path", paths.hasNext());
assertPath(algo.findSinglePath(nodeA, nodeC), nodeA, nodeB, nodeC);
}
@Test
public void canGetMultiplePathsInASmallRoadNetwork() throws Exception {
Node nodeA = graph.makeNode("A");
Node nodeB = graph.makeNode("B");
Node nodeC = graph.makeNode("C");
Node nodeD = graph.makeNode("D");
Node nodeE = graph.makeNode("E");
Node nodeF = graph.makeNode("F");
graph.makeEdge("A", "B", "length", 2d);
graph.makeEdge("A", "C", "length", 2.5d);
graph.makeEdge("C", "D", "length", 7.3d);
graph.makeEdge("B", "D", "length", 2.5d);
graph.makeEdge("D", "E", "length", 3d);
graph.makeEdge("C", "E", "length", 5d);
graph.makeEdge("E", "F", "length", 5d);
graph.makeEdge("C", "F", "length", 12d);
graph.makeEdge("A", "F", "length", 25d);
Dijkstra algo =
new Dijkstra(
PathExpanders.allTypesAndDirections(), CommonEvaluators.doubleCostEvaluator("length"));
// Try the search in both directions.
for (Node[] nodes : new Node[][] {{nodeA, nodeF}, {nodeF, nodeA}}) {
int found = 0;
Iterator<WeightedPath> paths = algo.findAllPaths(nodes[0], nodes[1]).iterator();
for (int i = 0; i < 2; i++) {
assertTrue("expected more paths", paths.hasNext());
Path path = paths.next();
if (path.length() != found && path.length() == 3) {
assertContains(path.nodes(), nodeA, nodeC, nodeE, nodeF);
} else if (path.length() != found && path.length() == 4) {
assertContains(path.nodes(), nodeA, nodeB, nodeD, nodeE, nodeF);
} else {
fail("unexpected path length: " + path.length());
}
found = path.length();
}
assertFalse("expected at most two paths", paths.hasNext());
}
}
/** Test case for paths of length 0 and 1, and an impossible path */
@Test
public void testMinimal() {
graph.makeEdge("a", "b", "cost", (double) 1);
graph.makeEdge("a", "c", "cost", (double) 1);
graph.makeEdge("a", "d", "cost", (double) 1);
graph.makeEdge("a", "e", "cost", (double) 1);
graph.makeEdge("b", "c", "cost", (double) 1);
graph.makeEdge("c", "d", "cost", (double) 1);
graph.makeEdge("d", "e", "cost", (double) 1);
graph.makeEdge("e", "b", "cost", (double) 1);
FloydWarshall<Double> floydWarshall =
new FloydWarshall<Double>(
0.0,
Double.MAX_VALUE,
Direction.OUTGOING,
CommonEvaluators.doubleCostEvaluator("cost"),
new org.neo4j.graphalgo.impl.util.DoubleAdder(),
new org.neo4j.graphalgo.impl.util.DoubleComparator(),
graph.getAllNodes(),
graph.getAllEdges());
assertTrue(floydWarshall.getCost(graph.getNode("a"), graph.getNode("a")) == 0.0);
assertTrue(floydWarshall.getCost(graph.getNode("a"), graph.getNode("b")) == 1.0);
assertTrue(floydWarshall.getCost(graph.getNode("b"), graph.getNode("a")) == Double.MAX_VALUE);
}