如图所示，如何用cypher查从B到D的最短路径？
shortestpath（） 是不行的，因为那个只能查没有权值的。
shortestpath()方法只能查 关系的“跳数”最少的路径，要按照自己权重查最优路径，就遍历全部路径，然后用reduce（）方法筛选 比如下列方法不能用：
MATCH (start:Point {title: ‘Some Point 1’}), (end:Point {title: ‘Some Point 5’}) MATCH p=shortestPath((start)-[:distance*]->(end)) RETURN p
替换方法可以为：
MATCH (start:Point {title: ‘Some Point 1’}), (end:Point {title: ‘Some Point 5’}) MATCH p=(start)-[:distance*]->(end) WITH p,reduce(s = 0, r IN rels( p) | s + r.value) AS dist RETURN p, dist ORDER BY dist DESC
或者可以采用 APOC
MATCH (start:Point {title: ‘Some Point 1’}), (end:Point {title: ‘Some Point 5’}) CALL apoc.algo.dijkstra(start, end, ‘distance’, ‘value’) YIELD path, weight RETURN path, weight
match (d19:device{id:“19”}),(d20:device{id:“20”}),p=((d19)-[*1…10]->(d20)) with reduce(tot = 0, n IN rels§| tot + n.RC) AS ref, p return p order by ref asc limit 1
二楼的稍微有点问题，应该加个return就OK了。
针对主楼发的那个图，Cypher语言如下。 创建节点 Create(b:device{id:‘B’,name:‘X62W’,X:4,Y:10}) Create(e:device{id:‘E’,name:‘X62W’,X:18,Y:10}) Create(c:device{id:‘C’,name:‘X62W’,X:24,Y:10}) Create(d:device{id:‘D’,name:‘X62W’,X:40,Y:10}) Create(a:device{id:‘A’,name:‘X62W’,X:36,Y:5})
添加关系 match(b:device{id:‘B’,name:‘X62W’,X:4,Y:10}) match(e:device{id:‘E’,name:‘X62W’,X:18,Y:10}) match(c:device{id:‘C’,name:‘X62W’,X:24,Y:10}) match(d:device{id:‘D’,name:‘X62W’,X:40,Y:10}) match(a:device{id:‘A’,name:‘X62W’,X:36,Y:5}) create (b)-[:to{RC:14}]->(e) create (e)-[:to{RC:14}]->(b) create (e)-[:to{RC:6}]->© create ©-[:to{RC:6}]->(e) create ©-[:to{RC:16}]->(d) create (d)-[:to{RC:16}]->© create (d)-[:to{RC:9}]->(a) create (a)-[:to{RC:9}]->(d) create (a)-[:to{RC:37}]->(b) create (b)-[:to{RC:37}]->(a)
查询B节点到D节点的最短路径 match (b:device{id:“B”}),(d:device{id:“D”}),p=((b)-[*1…10]->(d)) with reduce(tot = 0, n IN rels§| tot + n.RC) AS ref, p return p order by ref asc limit 1
