Question

给出以下图表：

可通过以下Cypher脚本创建：

CREATE
    (n1:Token {content: "lonely"}),
    (n2:Token {content: "island"}),
    (n1)-[:PRECEDES]->(n2);


CREATE
    (n1:Token {content: "the"}),
    (n2:Token {content: "quick"}),
    (n3:Token {content: "brown"}),
    (n4:Token {content: "fox"}),
    (n5:Token {content: "bear"}),
    (n1)-[:PRECEDES]->(n2),
    (n2)-[:PRECEDES]->(n3),
    (n3)-[:PRECEDES]->(n4),
    (n3)-[:PRECEDES]->(n5);

我想要一个查询，它将返回来自给定根目录的路径中的节点 PRECEDES关系倒退。查询应该也全部返回给定节点的传入关系，以便我可以构造子图在内存中以后。但是，传入关系列表永远不应该指向在返回的根之外。

例如，如果我查询根lonely，我想要结果：

+-----------------------------------------------------------------------+
| (:Token {content: "lonely"}) | []                                     |
| (:Token {content: "island"}) | [[:PRECEDES]]                          |
+-----------------------------------------------------------------------+

如果我查询根the，我想要结果：

+-----------------------------------------------------------------------+
| (:Token {content: "the"})   | []                                      |
| (:Token {content: "quick"}) | [[:PRECEDES]]                           |
| (:Token {content: "brown"}) | [[:PRECEDES]]                           |
| (:Token {content: "fox"})   | [[:PRECEDES]]                           |
| (:Token {content: "bear"})  | [[:PRECEDES]]                           |
+-----------------------------------------------------------------------+

如果我查询根brown，我想要以下结果，请注意 brown本身的传入关系已被省略，因为它会点在子图之外。

+-----------------------------------------------------------------------+
| (:Token {content: "brown"}) | []                                      |
| (:Token {content: "fox"})   | [[:PRECEDES]]                           |
| (:Token {content: "bear"})  | [[:PRECEDES]]                           |
+-----------------------------------------------------------------------+

根节点和叶节点应始终包含在结果中。

这是我到目前为止的尝试：

MATCH (a:Token {content: {root}})-[:PRECEDES*]->(t:Token)
WITH COLLECT(a) + COLLECT(DISTINCT t) AS nodes_
UNWIND nodes_ AS n
OPTIONAL MATCH p = (n)-[r]-()
WITH n AS n2, COLLECT(DISTINCT RELATIONSHIPS(p)) AS nestedrel
RETURN n2, REDUCE(output = [], rel in nestedrel | output + rel) AS rels

这种情况很接近但有几个问题：使用COLLECT(a) 人为地包括根是一种hacky，它留下了关系在关系结果中指向远离根，并且如果您尝试使用a 叶节点作为根它赢得了根本不返回任何节点。（REDUCE部分是只需将关系列表展平一级。）

[仅供参考，我需要在内存中重建这个树结构作为 NetworkX MultiDiGraph。]

查询返回子图和所有内部关系

0 个答案: