[英]Can't find the lightest path in Neo4j with cypher
我試圖在下圖中找到從節點a
到e
的最輕路徑:
結果應為13:
a -> b: 1
b -> c: 3
c -> d: 4
d -> e: 5 (take lighter edge)
----------
13
我嘗試了幾個示例(例如https://neo4j.com/docs/graph-algorithms/current/algorithms/shortest-path/ ),但是找不到正確的查詢。
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
結果是
╒═════════════╤════════════╤═══════════╤═══════════╕
│"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
結果是
╒═════════════╤════════════╤═══════════╤═══════════╕
│"writeMillis"│"loadMillis"│"nodeCount"│"totalCost"│
╞═════════════╪════════════╪═══════════╪═══════════╡
│3 │19 │4 │14.0 │
└─────────────┴────────────┴───────────┴───────────┘
其他類似以下查詢甚至都不返回任何內容:
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
我想看到一個返回“ 13”作為解決方案的查詢,理想情況下將顯示所選的路徑,如下所示:
我該如何實現?
非常感謝你。
該查詢:
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
返回此結果:
╒══════════════════════════════════════════════════════════════════════╤═════════════╕
│"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瀏覽器中,如果禁用“ 連接結果節點”選項(位於“瀏覽器設置”窗格的底部,可通過單擊左側面板中的齒輪圖標來顯示該選項),則可視化效果為:
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