Neo4j 在树中，使用密码计算每个节点到根的距离

给一棵这样的树

     a
    / \
   b   c
  / \
 d   e
 |
 f

我想编写一个返回我的密码查询：

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startPoint的任何特定顺序）

假设您的关系在树中是“向下”的，并且每个节点都有一个

id

属性，那么这应该可以工作：

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;

---

请详细说明您在做“想做”的事情时面临的问题，并访问以了解如何更清楚地表达您的问题。。

+-------------------------------------------------------------------------------------------+
| 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}]                                 |
+-------------------------------------------------------------------------------------------+