获取节点按接近度排序，同级别按日期排序

Question

我是 neo4j 的新手，我很难为我的查询获得良好的结果。我有下一个型号：

Player <- HAS_PLAYERS - Game

Node Player: playerId, name,...etc
Node Game: gameId, gameDate
Rel. HAS_PLAYERS: result

请注意，一个游戏可以有 1-4 名玩家。

我想查询以向以下命令的玩家推荐未来的对手：以前的对手按 gameDate 排序（最近），然后对手的对手按 gameDate 排序。

例如：

PlayerA <- 2021/02/01 -> PlayerB*
PlayerA <- 2021/02/01 -> PlayerC*
PlayerA <- 2021/02/11 -> PlayerB

PlayerB <- 2021/02/04 -> PlayerC
PlayerB <- 2021/02/20 -> PlayerD

PlayerC <- 2021/02/15 -> PlayerD
PlayerC <- 2021/12/01 -> PlayerE

PlayerD <- 2021/02/07 -> PlayerE
PlayerD <- 2021/02/23 -> PlayerF

* = Same game

The result would be:

PlayerB
PlayerC
PlayerE
PlayerD

说明： PlayerB和PlayerC曾经是对手，但PlayerB是第一个，因为上一场比赛比PlayerC更近。

PlayerE和PlayerD是对手，PlayerE是之前，因为下一场比赛是在12月。

我有下一个查询，但我的问题是查询 returns 重复节点:

# Getting direct opponents
MATCH (p:Player {userId: "PlayerA"})<-[:HAS_PLAYERS]-(g:Game)-[:HAS_PLAYERS]->(o:Player)
WITH p, o, g ORDER BY g.gameDate DESC 
WITH p, COLLECT(o) AS opponents
# Getting opponents-of-opponents (ops)
MATCH (p)-[:HAS_PLAYERS*3]-(gops:Game)--(ops:Player)
WHERE p.userId <> ops.userId AND NOT ops IN opponents
# Trying to remove duplicated nodes
WITH DISTINCT ops, opponents, gops
WITH opponents, ops, gops ORDER BY gops.gameDate DESC
# Concat both lists: opponents and opponents-of-opponents
WITH REDUCE(s = opponents, o2 IN COLLECT(ops) | s + o2) as listAllOpponents
UNWIND listAllOpponents as opPlayer
RETURN opPlayer

它returns类似于：

PlayerB
PlayerC
PlayerD
PlayerE
PlayerD

如有任何帮助，我们将不胜感激。

Answer 1

当您聚合节点时，它不会删除重复项，因此添加关键字“distinct”将修复它。代替 COLLECT(o)，使用 COLLECT(DISTINCT o) 作为对手并使用 COLLECT(DISTINCT ops)。

// Getting direct opponents
MATCH (p:Player {userId: "34618"})<-[:HAS_PLAYERS]-(g:Game)-[:HAS_PLAYERS]->(o:Player)
WITH p, o, g ORDER BY g.gameDate DESC 
WITH p, COLLECT(DISTINCT o) AS opponents
// Getting opponents-of-opponents (ops)
MATCH (p)-[:HAS_PLAYERS*3]-(gops:Game)--(ops:Player)
WHERE p.userId <> ops.userId AND NOT ops IN opponents
// Trying to remove duplicated nodes
WITH DISTINCT ops, opponents, gops
WITH opponents, ops, gops ORDER BY gops.gameDate DESC
// Concat both lists: opponents and opponents-of-opponents
WITH REDUCE(s = opponents, o2 IN COLLECT(DISTINCT ops) | s + o2) as listAllOpponents
UNWIND listAllOpponents as opPlayer
RETURN opPlayer

Result:
   PlayerB
   PlayerC
   PlayerE
   PlayerD

Answer 2

这是我的解决方案：

# Getting direct opponents
MATCH (p:Player {userId: "PlayerA"})<-[:HAS_PLAYERS]-(g:Game)-[:HAS_PLAYERS]->(o:Player)
WITH p, o, max(g.gameDate) as maxDate
WITH p, o ORDER BY maxDate DESC
WITH p, COLLECT(o) AS opponents
# Getting opponents-of-opponents (ops)
OPTIONAL MATCH (p)-[:HAS_PLAYERS*3]-(gops:Game)--(ops:Player)
WHERE p.userId <> ops.userId AND NOT ops IN opponents
WITH opponents, ops, max(gops.start) as maxDate
WITH opponents, ops ORDER BY maxDate DESC
WITH opponents, COLLECT(ops) AS opponentsOfOpponents
# Concat both lists: opponents and opponents-of-opponents
UNWIND (opponents + opponentsOfOpponents) AS player
RETURN player

获取节点按接近度排序，同级别按日期排序

Get nodes sorted by proximity and at the same level sort by date

neo4j

cypher