Collections Neo4j中的并集和计数集合

我的简单数据库包含相互链接的“术语”和“代码”节点。 有两种类型的关系

“术语”和“代码”之间的关系称为：代码和是无向的（或在两个方向上读取相等）。 “术语”之间的关系称为：NT（意思是狭义术语）和直接的

我想从上到下遍历所有的“术语”，收集所有唯一的代码并计算它们

这是我的疑问：

MATCH (a)-[:NT*]->(b), (a)-[:CODE]-(c), (b)-[:CODE]-(d)
WHERE a.btqty = 0
RETURN a.termid AS termid, a.maxlen AS maxlen, COUNT(DISTINCT c.code) + COUNT(DISTINCT d.code) AS total, COLLECT(DISTINCT c.code) + COLLECT(DISTINCT d.code) AS codes
ORDER BY termid;

这就是我得到的：

termid  maxlen  total   codes
22  2   3   ["S70","S43","S70"]
25  4   9   ["S20","S21","S54","S61","S63","S63","S21","S61","S54"]
26  2   9   ["S99","S98","S29","S13","S13","S20","S29","S14","S15"]
68  5   13  ["S38","S11","S12","S11","S12","S38","S37","S21","S36","S22","S98","S63","S58"]
123 2   3   ["S38","S12","S12"]
154 2   2   ["S58","S58"]
155 4   3   ["S63","S62","S63"]
159 2   2   ["S36","S36"]
...

我需要清除集合中的重复项，并按如下方式正确计数：

termid  maxlen  total   codes
22  2   2   ["S43","S70"]
25  4   5   ["S20","S21","S54","S61","S63"]
26  2   7   ["S99","S98","S29","S13","S20","S14","S15"]
68  5   10  ["S38","S11","S12","S37","S21","S36","S22","S98","S63","S58"]
123 2   2   ["S38","S12"]
154 2   1   ["S58"]
155 4   2   ["S63","S62"]
159 2   1   ["S36"]
...

我认为这是关于REDUCE函数的应用，但我不知道如何使用它

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谢谢你的帮助

你说得对，这可以用

REDUCE

解决。在reduce中，您需要检查累加器中是否已经存在当前元素，并有条件地修改它：

MATCH (a)-[:NT*]->(b), (a)-[:CODE]-(c), (b)-[:CODE]-(d)
WHERE a.btqty = 0
WITH a.termid AS termid, a.maxlen AS maxlen, 
   REDUCE(uniqueCodes=[], 
         x in COLLECT(DISTINCT c.code) + COLLECT(DISTINCT d.code) |
          CASE WHEN x IN uniqueCodes THEN uniqueCodes ELSE uniqueCodes+x END
   ) AS codes
ORDER BY termid
RETURN termid, maxlen, count(codes) as total, codes

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非常感谢！现在我知道REDUCE是如何工作的了。顺便说一句，从长度（代码）到总计数（代码）。非常感谢你！！！