有一个图,它的每个节点都包含属性
communityId
来指示该节点属于哪个社区。节点之间以LINK
关系连接,其中包含weight
属性。
我想要的是将那些同一个社区的节点合并成一个大节点。这些大节点(又名社区)之间的链接必须合理地合成/组合:链接的
weight
属性必须根据每个社区中相互连接的各个节点进行累加。必须尊重链接的方向。
在结果图中,我只会看到连接的 community 节点。
最接近的函数是Merge Nodes,函数
apoc.refactor.mergeNodes()
。然而,我对结果不满意,因为:
问题1可以通过再编写一个Cypher来删除自链接来解决。但问题 2 只能通过对图的低级访问来解决(如上面的
mergeNodes()
)。
是否有任何优雅的方法可以一次性获得我想要的图表(社区节点)?或者至少,问题 2 必须以某种方式得到解决。
再现性
CREATE (a:User {name: "A", communityId: 2}), (b:User {name: "B", communityId: 2}), (c:User {name: "C", communityId: 2}), (x:User {name: "X", communityId: 1}), (y:User {name: "Y", communityId: 1}), (z:User {name: "Z", communityId: 1}), (w:User {name: "W", communityId: 1}), (a)-[:LINK {weight: 1}]->(b), (b)-[:LINK {weight: 1}]->(c), (c)-[:LINK {weight: 1}]->(a), (b)-[:LINK {weight: 1}]->(z), (z)-[:LINK {weight: 1}]->(x), (z)-[:LINK {weight: 1}]->(w), (w)-[:LINK {weight: 1}]->(y), (y)-[:LINK {weight: 1}]->(x), (b)-[:LINK {weight: 1}]->(w)
密码:
MATCH (n:User)
WITH n.communityId AS communityId, COLLECT(n) AS nodes
CALL apoc.refactor.mergeNodes(nodes, {
properties: {
name: 'combine',
communityId: 'discard',
weight: 'combine'
},
mergeRels: true
})
YIELD node
RETURN node
系统要求
MATCH (n:User)-[r]->(v:User)
WHERE n.communityId <> v.communityId // discard self loop
WITH n.communityId as comId1, v.communityId as comId2, sum(r.weight) as w
MERGE (su1:SuperUser {communityId: comId1}) // create or get merged node for n.communityId
MERGE (su2:SuperUser {communityId: comId2}) // create or get node for v.communityId
MERGE (su1)-[r:SUPER_LINK]->(su2)
ON CREATE SET r.weight = w // set relationship weight when it is created
RETURN su1, su2, r
创建以下节点和关系: