neo4j -return语句中两个集合之间的差异

juzqafwq 于 2022-11-05 发布在其他

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我有一个模式：主题有帖子，用户写主题和帖子。我想找到推荐的主题。在我的例子中，我返回count（topics）和count（rec_topics）。怎么可能返回这两个集合之间的差呢？比如[1,2] - [1] = [2]谢谢

MATCH (user:User {first_name: 'Hlavní' }),
user<-[:wrote_by]-(posts:Post)<-[:TOPIC]-(topics:Topic)-[:TOPIC]->(all_posts:Post)-[:wrote_by]->(friends:User)<-[:wrote_by]-(friends_posts:Post)<-[:TOPIC]-(rec_topics:Topic)
WHERE NOT(topics=rec_topics)
RETURN count(DISTINCT topics),count(DISTINCT rec_topics);

neo4j

来源：https://stackoverflow.com/questions/28894098/neo4j-difference-between-two-sets-in-return-statement

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按热度按时间

rsaldnfx1#

你可以使用collect为topics和rec_topics建立一个集合。在第二步中，可以使用列表解析只返回那些不属于rec_topics的主题：

MATCH (user:User {first_name: 'Hlavní' }),
  user<-[:wrote_by]-(posts:Post)<-[:TOPIC]-(topics:Topic)-[:TOPIC]->       
  (all_posts:Post)-[:wrote_by]->(friends:User)<-[:wrote_by]-  
  (friends_posts:Post)<-[:TOPIC]-(rec_topics:Topic)
WHERE NOT(topics=rec_topics)
WITH collect(DISTINCT topics) as topics, collect(distinct rec_topics) as rec_topics
RETURN [x in topics WHERE not(x in rec_topics)] as delta, 
       length(topics), length(rec_topics)

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neo4j -return语句中两个集合之间的差异

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