Gremlin 合并两个遍历

Question

我有 2 个遍历：1 个按标签查找顶点，另一个按标签查找边，我正在尝试合并它们，即获取具有 vertexlabel 的顶点的所有 edgeLabel 边strong> 标签。

顶点遍历：

graph.traversal().V().hasLabel("vertexLabel")

边遍历函数（必须是不同的函数）：

private GraphTraversal<Vertex, Edge> getEdges() {
    return __.inE("edgeLabel");
}

我尝试了以下方法，但没有成功

graph.traversal().V().hasLabel("vertexLabel").and(getEdges())

Answer 1

您可以使用and 或filter（取决于您正在遍历的具体Traversal）

TinkerGraph g = TinkerGraph.open();

/*
         u:A
<1:A> ---------- <2:B>
  |                |
  | x:B            | v:B
  |                |
<4:B> ---------- <3:A>
         w:A
*/

Vertex v1 = g.addVertex(T.label, "A", T.id, 1);
Vertex v2 = g.addVertex(T.label, "B", T.id, 2);
Vertex v3 = g.addVertex(T.label, "A", T.id, 3);
Vertex v4 = g.addVertex(T.label, "B", T.id, 4);

v1.addEdge("A", v2, T.id, "u");
v2.addEdge("B", v3, T.id, "v");
v3.addEdge("A", v4, T.id, "w");
v4.addEdge("B", v1, T.id, "x");

// predefined traversal from somewhere
Traversal<Vertex, Vertex> vertexFilter = __.hasLabel("A");
Traversal<Vertex, Vertex> edgeFilter = __.hasLabel("B");
Traversal<Vertex, Edge> vertex2edges = __.bothE().filter(edgeFilter);
Traversal<Edge, Vertex> edge2vertex = __.bothV().filter(vertexFilter);

System.out.println("Get edges matching filter with any vertex matching filter:");
g.traversal().E().filter(edgeFilter).and(edge2vertex).toList()
        .forEach(e -> System.out.printf(" - %s%n", e.id()));

System.out.println("Get vertex matching filter with any edge matching filter:");
g.traversal().V().filter(vertexFilter).and(vertex2edges).toList()
        .forEach(v -> System.out.printf(" - %s%n", v.id()));

有输出

Get edges matching filter with any vertex matching filter:
 - v
 - x
Get vertex matching filter with any edge matching filter:
 - 1
 - 3