jgrapht顶点的全部路径

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import org.apache.commons.collections.CollectionUtils;
import org.jgrapht.Graph;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;

import java.util.List;
import java.util.stream.Collectors;

/**
 * @ClassName: GraphXPUtils
 * @author kanpiaoxue
 * @version 1.0
 * @CreateTime: 2019/09/03 15:50:36
 * @Description: Graph工具类
 */
public class GraphXPUtils {

    private static final int ZERO = 0;

    /**
     *
     */
    private GraphXPUtils() {
        super();
    }

    /**
     * 找到图中的叶子节点
     *
     * @param 
     * @param 
     * @param graph
     * @return
     * @author kanpiaoxue
     * @CreateTime: 2019/09/03 15:53:08
     * @Description: 图中的叶子节点：它们的出度为 0
     */
    public static  List findLeaves(Graph graph) {
        Preconditions.checkNotNull(graph, "graph is null");
        if (CollectionUtils.isEmpty(graph.vertexSet())) {
            return Lists.newArrayList();
        }
        return graph.vertexSet().stream().filter(v -> {
            return graph.outDegreeOf(v) == ZERO;
        }).collect(Collectors.toList());
    }

    /**
     * 找到图中的根节点
     *
     * @param 
     * @param 
     * @param graph
     * @return
     * @author kanpiaoxue
     * @CreateTime: 2019/09/03 15:53:08
     * @Description: 图中的根节点：它们的入度为 0
     */
    public static  List findRoots(Graph graph) {
        Preconditions.checkNotNull(graph, "graph is null");
        if (CollectionUtils.isEmpty(graph.vertexSet())) {
            return Lists.newArrayList();
        }
        return graph.vertexSet().stream().filter(v -> {
            return graph.inDegreeOf(v) == ZERO;
        }).collect(Collectors.toList());
    }
}

 

 

全部路径的示例代码：

 public static void test021() throws Exception {
        Graph g = new DirectedAcyclicGraph(DefaultEdge.class);
        IntStream.rangeClosed(1, 13).forEach(v -> {
            g.addVertex(v);
        });
        /**
         * 
         *  
         * [示意图]：当前Graph是有向无环图(DAG)，方向是：从上到下。 
         * -- predecessor:upstream 
         * 
         *  8   1   5   7   9   11 
         *  | / | \  \ /    | 
         *  2   3  4  6     10 
         *  |   | 
         *  12  | 
         *    \ | 
         *     13 
         * 
         * -- successor:downstream
         * 
         * 
         */
        g.addEdge(8, 2);
        g.addEdge(1, 2);
        g.addEdge(1, 3);
        g.addEdge(1, 4);
        g.addEdge(5, 6);
        g.addEdge(7, 6);
        g.addEdge(9, 10);
        g.addEdge(2, 12);
        g.addEdge(3, 13);
        g.addEdge(12, 13);

        // 目标顶点
        Integer targetVertex = 13;
        // 双连通性检查器
        BiconnectivityInspector in = new BiconnectivityInspector<>(g);
        System.out.println(StringUtils.repeat("=", 100));
        // 根据目标顶点得到它的连通图。
        Graph g2 = in.getConnectedComponent(targetVertex);
        System.out.println(String.format("targetVertex:%s, 连通图：%s", targetVertex, g2));
        // 由于当前连通图 g2 是个无向图，需要将它转换为DAG有向图，采用子图的方式转换为g3的DAG
        Graph g3 = new AsSubgraph(g, g2.vertexSet());
        System.out.println(String.format("targetVertex:%s, 连通DAG图：%s", targetVertex, g3));
        /**
         * 
         *  
         *  g2 ---> output 
         *  ([1, 2, 3, 4, 8, 12, 13], [{1,2}, {1,3}, {1,4}, {8,2}, {12,13}, {2,12}, {3,13}])
         *  g3 ---> output 
         *  ([1, 2, 3, 4, 8, 12, 13], [(8,2), (1,2), (1,3), (1,4), (2,12), (3,13), (12,13)])
         *  [注意] g2 和 g3 在边的打印上面的区别： 
         *      g2是无向图，边的关系使用花括号表示，如：{12,13}
         *      g3是有向图，边的关系使用实括号表示，如：(12,13)
         *      有向图和无向图edge打印的区别可以查看下面的源代码：
         *      org.jgrapht.graph.AbstractGraph.java#toString()
         * 
         */
        // 计算所有路径采用 AllDirectedPaths 来获得
        AllDirectedPaths allPaths = new AllDirectedPaths(g);
        // 找到新的DAG图中的所有root顶点
        List roots = GraphXPUtils.findRoots(g3);
        System.out.println(String.format("roots:%s", roots));
        // 在新的DAG图中对所有root顶点进行遍历，查找它们到目标顶点的所有的路径
        roots.forEach(root -> {
            System.out.println(StringUtils.repeat("=", 100));
            List> paths =
                    allPaths.getAllPaths(root, targetVertex, true, null);
            paths.forEach(p -> {
                System.out.println(String.format("root:%s,targetVertex:%s,path:%s", root, targetVertex, p));
            });
        });

    }