apoc.agg.median

详细信息

语法

apoc.agg.median(value)

描述

返回所有非空 INTEGER(整数)和 FLOAT(浮点数)值的数学中位数。

参数

名称

类型

描述

ANY

要聚合的值。

返回

ANY

用法示例

本节中的示例基于以下示例图

CREATE (Keanu:Person {name:'Keanu Reeves', born:1964})
CREATE (TomH:Person {name:'Tom Hanks', born:1956})

CREATE (TheDevilsAdvocate:Movie {title:"The Devil's Advocate", released:1997, tagline:'Evil has its winning ways'})
CREATE (TheMatrix:Movie {title:'The Matrix', released:1999, tagline:'Welcome to the Real World'})
CREATE (TheMatrixReloaded:Movie {title:'The Matrix Reloaded', released:2003, tagline:'Free your mind'})

CREATE (SleeplessInSeattle:Movie {title:'Sleepless in Seattle', released:1993, tagline:'What if someone you never met, someone you never saw, someone you never knew was the only someone for you?'})
CREATE (ThatThingYouDo:Movie {title:'That Thing You Do', released:1996, tagline:'In every life there comes a time when that thing you dream becomes that thing you do'})
CREATE (YouveGotMail:Movie {title:"You've Got Mail", released:1998, tagline:'At odds in life... in love on-line.'})

CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrix)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixReloaded)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheDevilsAdvocate)

CREATE (TomH)-[:ACTED_IN {roles:['Joe Fox']}]->(YouveGotMail)
CREATE (TomH)-[:ACTED_IN {roles:['Sam Baldwin']}]->(SleeplessInSeattle)
CREATE (TomH)-[:ACTED_IN {roles:['Mr. White']}]->(ThatThingYouDo);

我们可以通过运行以下查询,找到每个人参演电影的发行年份的中位数:

apoc.agg.median
MATCH (p:Person)-[:ACTED_IN]->(movie)
RETURN p.name AS person, apoc.agg.median(movie.released) AS medianReleaseYear
Cypher 的 COLLECT 子查询和 CASE 表达式
MATCH (p:Person)
WITH p, COLLECT { MATCH (p)-[:ACTED_IN]->(movie) RETURN movie.released ORDER BY movie.released } AS releasedYears
WITH p.name AS name, releasedYears, size(releasedYears) AS size
RETURN name,
    CASE size % 2
        WHEN 1 THEN releasedYears[size / 2]
        ELSE (releasedYears[size / 2 - 1] + releasedYears[size / 2]) / 2
    END AS medianReleaseYear
结果
person medianReleaseYear(中位发行年份)

"Keanu Reeves"

1999.0

"Tom Hanks"

1996.0