neo4j - NodeProperties in gds.alpha.shortestPath.stream

Question

The Neo4j Data Graph Science library has an Shortest Path algorithm (https://neo4j.com/docs/graph-data-science/current/alpha-algorithms/shortest-path/). The following sequence is the example algorithm which works for my project:

MATCH (start:Loc {name: 'A'}), (end:Loc {name: 'F'})
CALL gds.alpha.shortestPath.stream({
  nodeProjection: 'Loc',
  relationshipProjection: {
    ROAD: {
      type: 'ROAD',
      properties: 'cost',
      orientation: 'UNDIRECTED'
    }
  },
  startNode: start,
  endNode: end,
  relationshipWeightProperty: 'cost'
})
YIELD nodeId, cost
RETURN gds.util.asNode(nodeId).name AS name, cost

The problem is that the graph has to be filtered before finding the shortest path. Every node has an attribute called currentWeather and every node with currentWeather = "good" is a valid node for the shortest path.

Is it possible to use e.g. the nodeProperties to filter for currentWeather = "good"? And if that does not work, how would you create a subgraph or filter for nodes with currentWeather = "good"?

Many thanks in advance

Answer 1

You will need to use cypher projection to filter the subgraph.

MATCH (start:Loc {name: 'A'}), (end:Loc {name: 'F'})
CALL gds.alpha.shortestPath.stream({
  nodeQuery: 'Match (l:Loc) Where l.currentWeather = 
        "Good" return id(l) as id',
    relationshipQuery: 'match (l:Loc)-[r:ROAD]-(t:Loc) return id(l) as source, id(t) as target, r.cost as cost',
     startNode: start,
     endNode: end,
    relationshipWeightProperty: 'cost'
  })
  YIELD nodeId, cost
   RETURN gds.util.asNode(nodeId).name AS name, cost