Question

我目前正在尝试使用电影的neo4j数据集示例创建查询。我想选择带有很多标签的电影（更受欢迎）以及评分较低的电影。

我已经弄清楚如何找到最受欢迎的（超过平均值）：

MATCH (m:MOVIE)-[r:HAS_TAG]->() 
WITH count(r) as tagnum, m.title as title_now
WITH avg(tagnum) as avgtagnum
MATCH (m:MOVIE)-[r:HAS_TAG]->() 
WITH count(r) as tagnum, m.title as title_now, avgtagnum
WHERE tagnum > avgtagnum*3
RETURN title_now, avgtagnum, tagnum 
ORDER BY  tagnum DESC

还有如何获得少注意的那些

MATCH ()-[r:RATED]->(m:MOVIE) 
WITH  avg(r.rating) as avgrating 
MATCH ()-[r:RATED]->(m:MOVIE) 
WITH m.title as titlemovie, avgrating, avg(r.rating) as  movierating 
WHERE movierating < avgrating/2
RETURN titlemovie, avgrating, movierating 
ORDER BY movierating ASC

但是当我将它们合并在一起时，查询永远不会结束。

MATCH ()-[r:RATED]->(m:MOVIE) 
WITH  avg(r.rating) as avgrating 
MATCH ()-[r:RATED]->(m:MOVIE) 
WITH m.title as titlemovie, avgrating, avg(r.rating) as  movierating 
WHERE movierating < avgrating/2
MATCH (m:MOVIE)-[r:HAS_TAG]->() 
WITH count(r) as tagnum, m.title as title_now, titlemovie, avgrating, movierating 
WITH avg(tagnum) as avgtagnum, titlemovie, avgrating, movierating 
MATCH (m:MOVIE)-[r:HAS_TAG]->() 
WITH count(r) as tagnum, m.title as title_now, avgtagnum, titlemovie, avgrating, movierating 
WHERE tagnum > avgtagnum*3
RETURN titlemovie, avgrating, movierating, avgtagnum, tagnum 
ORDER BY tagnum DESC,  movierating ASC

问题是如何找到符合我要求的电影;少注意，更受欢迎？

Answer 1

首先，使用平均（评分）会给你平均评分而不是电影的平均评分。

2。 MATCH (m:MOVIE)-[r:HAS_TAG]->() WITH count(r) as tagnum, ... WITH avg(tagnum) as avgtagnum ... 由于模式匹配，此代码不会为您提供完全平均的标记数量，只考虑那些带有某些标记的电影（因此您将获得比实际更大的平均数）。

为什么使用WITH ... m.title as title_now, titlemovie两个头衔？最好的猜测是你匹配错误的电影

如果必须纠正你的查询，我会这样写：

MATCH ()-[r:RATED]->(m:MOVIE) 
WITH  m, avg(r.rating) as avgra
with avg(avgra) as avgrating
MATCH (m:MOVIE) 
WITH avg(size((m)-[:HAS_TAG]-())) as avgtagnum, avgrating
MATCH (m:MOVIE)-[r:HAS_TAG]->() 
WITH count(r) as tagnum, m.title as titlemovie, avgtagnum, avgrating, avg(r.rating) as movierating
WHERE tagnum > avgtagnum*3 and movierating < avgrating/2
RETURN titlemovie, avgrating, movierating, avgtagnum, tagnum 
ORDER BY tagnum DESC,  movierating ASC

使用Cypher找到评分最低的最受欢迎的电影。合并查询

1 个答案: