jgrapht-獲取所有遍歷節點的列表

Question

以下是使用Dijkstra算法查找最短路徑的示例代碼：

public static void main(String args[]) {
    SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> graph = new SimpleDirectedWeightedGraph<String, DefaultWeightedEdge>(DefaultWeightedEdge.class);
    graph.addVertex("vertex1");
    graph.addVertex("vertex2");
    graph.addVertex("vertex3");
    graph.addVertex("vertex4");
    graph.addVertex("vertex5");

    DefaultWeightedEdge e1 = graph.addEdge("vertex1", "vertex2");
    graph.setEdgeWeight(e1, 5);

    DefaultWeightedEdge e2 = graph.addEdge("vertex2", "vertex3");
    graph.setEdgeWeight(e2, 3);

    DefaultWeightedEdge e3 = graph.addEdge("vertex4", "vertex5");
    graph.setEdgeWeight(e3, 6);

    DefaultWeightedEdge e4 = graph.addEdge("vertex2", "vertex4");
    graph.setEdgeWeight(e4, 2);

    DefaultWeightedEdge e5 = graph.addEdge("vertex5", "vertex4");
    graph.setEdgeWeight(e5, 4);

    DefaultWeightedEdge e6 = graph.addEdge("vertex2", "vertex5");
    graph.setEdgeWeight(e6, 9);

    DefaultWeightedEdge e7 = graph.addEdge("vertex4", "vertex1");
    graph.setEdgeWeight(e7, 7);

    DefaultWeightedEdge e8 = graph.addEdge("vertex3", "vertex2");
    graph.setEdgeWeight(e8, 2);

    DefaultWeightedEdge e9 = graph.addEdge("vertex1", "vertex3");
    graph.setEdgeWeight(e9, 10);

    DefaultWeightedEdge e10 = graph.addEdge("vertex3", "vertex5");
    graph.setEdgeWeight(e10, 1);

    System.out.println("Shortest path from vertex1 to vertex5:");
    List<DefaultWeightedEdge> shortest_path = DijkstraShortestPath.findPathBetween(graph,"vertex1", "vertex5");
    System.out.println(shortest_path);
}

是否有可能獲得已到達並被算法標記為已訪問節點的列表？ 我已經看到有一個稱為TraversalListener的東西，但它看起來僅適用於迭代器，例如Br​​eadthFirstIterator。

Answer 1

使用DijkstraShortestPath類似乎對此沒有任何DijkstraShortestPath 。 這是因為遍歷偵聽器已添加到圖形迭代器，並且DijkstraShortestPath使用的迭代器無法訪問。

這樣，唯一的解決方案是將DijkstraShortestPath代碼復制到新類中（我們將其MyDijkstraShortestPath ）並添加遍歷偵聽器。

首先，您需要創建一個繼承自TraversalListenerAdapter的類MyTraversalListener ，並覆蓋所需的方法。

class MyTraversalListener<V, E> extends TraversalListenerAdapter<V, E> {
     // override the method you want, like vertexTraversed and edgeTraversed
}

然后，在新的MyDijkstraShortestPath類的構造函數中，我們需要添加它：

ClosestFirstIterator<V, E> iter =
    new ClosestFirstIterator<V, E>(graph, startVertex, radius);
iter.addTraversalListener(new MyTraversalListener<V, E>());