Routing OpenStreetMapZero Cho

A quick recap on Graph

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How is routing done?

many ways. We will talk about A-star algorithm today.

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which leads us to my first result… A* OpenStreetMap router written in Ruby

https://github.com/itszero/osm-simple-router

https://github.com/itszero/osm-simple-router

which is great… except it’s…

so slow.

How do we improve it?

Moving to neo4j a Graph-based database.

Cypher Query Language

MATCH (actor:Person)-[:ACTED_IN]->(movie:Movie)WHERE movie.title =~ "T.*"RETURN movie.title as title, collect(actor.name) as castORDER BY title ASC LIMIT 10;

Sure it helps having proper storing and querying engine, but the data is still too much.

~25x improves? 5 secs?

intersections

overlay link

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take Atlanta metro area for an example

2,567,916 nodes ➔ 452,313 (-83%) 10,669,432 relationships ➔ 1,843,440 (-83%)

4.65 secs. routing time ➔ 1.30 secs.

Now we have the algorithm, all we need to do is plug it

into the database.

which leads us to my second result… A* OpenStreetMap router for Neo4j

https://github.com/itszero/neo4j-astar-example(code is really ugly tho)

https://github.com/itszero/neo4j-astar-example

Questions?