在树中，使用 Cypher 计算每个节点与根的距离

Question

给定这样一棵树

     a
    / \
   b   c
  / \
 d   e
 |
 f

我想写一个 Cypher 查询 returns 我:

startPoint: f, endPoint: a, path: [{f,3},{d,2},{b,1},{a,0}]
startPoint: d, endPoint: a, path: [{d,2},{b,1},{a,0}]
startPoint: e, endPoint: a, path: [{e,2},{b,1},{a,0}]
startPoint: b, endPoint: a, path: [{b,1},{a,0}]
startPoint: c, endPoint: a, path: [{c,1},{a,0}]

（以起点的任何特定顺序）

Answer 1

假设您的关系在树中是定向的 "downwards"，并且每个节点都有一个 id 属性，这应该有效：

MATCH p=(a)<-[*]-(b {id:'a'})
WITH a, b, NODES(p) AS pts, LENGTH(p) AS n
RETURN
  a.id AS startPoint,
  b.id AS endPoint,
  REDUCE(s = [], i IN RANGE(0, n) | s + {id: (pts[i]).id, depth: n-i}) AS path;

这是示例输出：

+-------------------------------------------------------------------------------------------+
| startPoint | endPoint | path                                                              |
+-------------------------------------------------------------------------------------------+
| "b"        | "a"      | [{id=b, depth=1},{id=a, depth=0}]                                 |
| "d"        | "a"      | [{id=d, depth=2},{id=b, depth=1},{id=a, depth=0}]                 |
| "f"        | "a"      | [{id=f, depth=3},{id=d, depth=2},{id=b, depth=1},{id=a, depth=0}] |
| "e"        | "a"      | [{id=e, depth=2},{id=b, depth=1},{id=a, depth=0}]                 |
| "c"        | "a"      | [{id=c, depth=1},{id=a, depth=0}]                                 |
+-------------------------------------------------------------------------------------------+

在树中，使用 Cypher 计算每个节点与根的距离

In a tree, calculate distance of each node from root, using Cypher

tree

neo4j

cypher