apoc.meta.data

过程

CREATE (Keanu:Person {name:'Keanu Reeves', born:1964})
CREATE (TomH:Person {name:'Tom Hanks', born:1956})
CREATE (Carrie:Person {name:'Carrie-Anne Moss', born:1967})
CREATE (Laurence:Person {name:'Laurence Fishburne', born:1961})
CREATE (Hugo:Person {name:'Hugo Weaving', born:1960})
CREATE (LillyW:Person {name:'Lilly Wachowski', born:1967})
CREATE (LanaW:Person {name:'Lana Wachowski', born:1965})

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 (TheMatrixRevolutions:Movie {title:'The Matrix Revolutions', released:2003, tagline:'Everything that has a beginning has an end'})
CREATE (SomethingsGottaGive:Movie {title:"Something's Gotta Give", released:2003})
CREATE (TheDevilsAdvocate:Movie {title:"The Devil's Advocate", released:1997, tagline:'Evil has its winning ways'})
CREATE (Something:Something:Else {foo: 'bar'})

CREATE (YouveGotMail:Movie {title:"You've Got Mail", released:1998, tagline:'At odds in life... in love on-line.'})
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 (CloudAtlas:Movie {title:'Cloud Atlas', released:2012, tagline:'Everything is connected'})

CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrix)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixReloaded)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixRevolutions)
CREATE (Keanu)-[:ACTED_IN {roles:['Julian Mercer']}]->(SomethingsGottaGive)
CREATE (Keanu)-[:ACTED_IN {roles:['Kevin Lomax']}]->(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)
CREATE (TomH)-[:ACTED_IN {roles:['Zachry', 'Dr. Henry Goose', 'Isaac Sachs', 'Dermot Hoggins']}]->(CloudAtlas)

CREATE (Keanu)-[:LIKES {rate:10}]->(Carrie)
CREATE (Keanu)-[:LIKES {rate:6}]->(TomH)
CREATE (Keanu)-[:LIKES {rate:4}]->(Laurence)
CREATE (Keanu)-[:LIKES {rate:8}]->(Hugo)
CREATE (Keanu)-[:LIKES {rate:9}]->(LillyW)
CREATE (Keanu)-[:LIKES {rate:6}]->(LanaW)
CREATE (Keanu)-[:LIKES {rate:100}]->(TheMatrix)
CREATE (Carrie)-[:LIKES {rate:7}]->(Keanu)

CREATE (Something)-[:RELATED_TO {rate:99}]->(TheMatrix)
CREATE (Keanu)-[:RELATED_TO {rate:12}]->(TheMatrix)
CREATE (Keanu)-[:RELATED_TO {rate:12}]->(TheMatrixReloaded)
CREATE (Keanu)-[:RELATED_TO {rate:23}]->(TheMatrixRevolutions)
CREATE (Carrie)-[:RELATED_TO {rate:34}]->(TheMatrix)
CREATE (TheMatrix)-[:RELATED_TO {rate:34}]->(Laurence)
CREATE (TheMatrixReloaded)-[:RELATED_TO {rate:345}]->(LanaW)

CALL apoc.meta.data();

MATCH p=(start:`<LABEL>`)-[:`<TYPE>`]->()
WITH count(distinct start) as nodes, count(p) as counts
RETURN CASE when nodes = 0 then 0 else counts / nodes end

MATCH p=(start:`<LABEL>`)<-[:`<TYPE>`]-()
WHERE exists((start:`<LABEL>`)-[:`<TYPE>`]->())
WITH count(distinct start) as nodes, count(p) as counts
RETURN CASE when nodes = 0 then 0 else counts / nodes end