Question

我试图在下图中找到从节点a到e的最短路径：

结果应为13：

a -> b:  1
b -> c:  3
c -> d:  4
d -> e:  5 (take lighter edge)
----------
        13

我尝试了几个示例（例如https://neo4j.com/docs/graph-algorithms/current/algorithms/shortest-path/），但是找不到正确的查询。

MATCH (start:LocationNode{name:'a'}), (end:LocationNode{name:'e'})
CALL algo.shortestPath(start, end, 'weight',{write:true,writeProperty:'sssp'})
YIELD writeMillis,loadMillis,nodeCount, totalCost
RETURN writeMillis,loadMillis,nodeCount,totalCost

产生

╒═════════════╤════════════╤═══════════╤═══════════╕
│"writeMillis"│"loadMillis"│"nodeCount"│"totalCost"│
╞═════════════╪════════════╪═══════════╪═══════════╡
│3            │3           │5          │12.0       │
└─────────────┴────────────┴───────────┴───────────┘

和

MATCH (start:LocationNode{name:'a'}), (end:LocationNode{name:'e'})
CALL algo.shortestPath(start, end, 'weight',{
nodeQuery:'MATCH(n:LocationNode) RETURN id(n) as id',
relationshipQuery:'MATCH(n:LocationNode)-[r:CONNECTED_TO]->(m:LocationNode) RETURN id(n) as source, id(m) as target, r.weight as weight',
graph:'cypher'})
YIELD writeMillis,loadMillis,nodeCount, totalCost
RETURN writeMillis,loadMillis,nodeCount,totalCost

产生

╒═════════════╤════════════╤═══════════╤═══════════╕
│"writeMillis"│"loadMillis"│"nodeCount"│"totalCost"│
╞═════════════╪════════════╪═══════════╪═══════════╡
│3            │19          │4          │14.0       │
└─────────────┴────────────┴───────────┴───────────┘

其他类似以下查询甚至不返回任何内容：

MATCH p=(LocationNode{name:'a'})-[:CONNECTED_TO*]->(LocationNode{name:'e'})
RETURN p as shortestPath,
REDUCE(weight=0, r in relationships(p) | weight+r.weight) AS totalDistance

我希望看到一个查询，该查询返回“ 13”作为解决方案，并且理想情况下会显示如下所示的所选路径：

我该如何实现？

非常感谢您。

Answer 1

此查询：

MATCH p=(a:LocationNode{name:'a'})-[:CONNECTED_TO*]->(e:LocationNode{name:'e'})
WITH p, REDUCE(s=0, r IN RELATIONSHIPS(p) | s + r.weight) AS totalWeight
RETURN p, totalWeight
ORDER BY totalWeight
LIMIT 1

返回此结果：

╒══════════════════════════════════════════════════════════════════════╤═════════════╕
│"p"                                                                   │"totalWeight"│
╞══════════════════════════════════════════════════════════════════════╪═════════════╡
│[{"name":"a"},{"weight":1},{"name":"b"},{"name":"b"},{"weight":3},{"na│13           │
│me":"c"},{"name":"c"},{"weight":4},{"name":"d"},{"name":"d"},{"weight"│             │
│:5},{"name":"e"}]                                                     │             │
└──────────────────────────────────────────────────────────────────────┴─────────────┘

在neo4j浏览器中，如果禁用Connect result nodes选项（在“浏览器设置”窗格的底部，您可以通过单击左侧面板中的齿轮图标来显示该选项），则可视化效果为：< / p>

用密码无法找到Neo4j中最轻的路径

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