CODEWITHSUNDEEP
neo4j
Ben
Ben

Reputation: 1581

Access relationship properties in shortest path search in neo4j

I am fairly new to Neo4j and I'm trying to build a small example app: a public transport planner. It looks as follows (obviously strongly simplified example):

simplified example

The departure and arrival time of each bus (trip) is stored as a relationship property. I want the bus to leave near (or after) a specified time, while arriving as soon as possible after the departure (i.e. not necessarily the shortest, but the fastest route).

I have experimented a lot in Cypher, but I have not been able to do this. Any advice?

EDIT: updated diagram

updated simplified example

Upvotes: 2

Views: 146

Answers (1)

cybersam
cybersam

Reputation: 67044

To enable a simpler Cypher query, you can change your graph model to something like:

(:Trip)-[:LEG {start: 10, end: 20}]->(:Stop)-[:LEG {start: 30, end: 40}]->(:Stop) ...
                                        |                                    |
                                      [:AT]                                [:AT]
                                        |                                    |
                                        v                                    v
                                (Location {name: "Paris"})           (Location {name: "London"})

To summarize, each Trip consists of a chain of N Legs and N Stops. Each Stop is related to a Location, and each Leg stores its start and end times.

With the above model, the following query will return: (a) the path of the fastest Trip that started at or after time 40, and (b) the duration of that Trip.

MATCH p=(t:Trip)-[legs:LEG*1..]->(s:Stop)-[:AT]->(loc:Location)
WHERE HEAD(legs).start >= 40 AND NOT (s)-[:LEG]->()
WITH p, LAST(legs).end - HEAD(legs).start AS duration
RETURN p, duration ORDER BY duration LIMIT 1;

Here is a console that shows sample results.

Upvotes: 2

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