Angelo, here is a ready made unmanaged extension to support A* via REST => http://maxdemarzi.com/2012/11/27/pathfinding-with-neo4j-unmanaged-extensions/
On Friday, January 10, 2014 5:45:04 AM UTC-6, Angelo Immediata wrote: > > Hi > > Thank yuo for replying me; maybe I was not too much clear so pardon me :) > I'll try to explain better our concern > > Regarding to the import phase (read and OSM file and create nodes and > relationships on neo4j), we already did it. Actually we can read and OSM > file and create a graph on neo4j; sure from the OSM we "take" only the > necessary data (e.g. ways and directions of the ways) and from these > necessary data we create our graph. > It's a slow process (on my laptop a 2GB OSM file is loaded in around 15 > hours by correctly settings memory heap both on JVM side and neo4j side). > To read the OSM file we used osmosis > > What is scaring us is the route calculation performances. > In fact we are worried if the neo4 implementation of dijkstra and/or A* > can guarantee good performances when we want to calcote the shortest path > between 2 points in the graph. Otherwise...should we use other algorithms > like bidirectional dijkstra or contraction hierarchy? If we should use > other algorithms....is there any implementation under neo4j? > > Thank you > Angelo > > > > Il giorno venerdì 10 gennaio 2014 09:34:08 UTC+1, Angelo Immediata ha > scritto: >> >> Hi there >> >> I'm using this environment: >> >> - spring 3.2.6 >> - spring-data-neo4j 2.3.3 (I'm thinking to upgrade to the version 3 >> in order to have support for neo4j 2.0) >> - neo4j 1.9.5 >> >> >> I'm thinking to use neo4j in order to store our own graph that will be >> used in a route planner project. The first question is if this seems to you >> (sure more experts than me) a good solution in order to build a very good >> and efficient and performant route planner >> Moreover as far as I know (by reading this link >> http://docs.neo4j.org/chunked/1.9.5/graph-algo.html ) in neo4j these >> algorithms are implemented: >> >> - Shortest paths >> - all paths >> - all simple paths >> - Dijkstra >> - A* >> >> >> By reading this link >> http://docs.neo4j.org/chunked/1.9.5/rest-api-graph-algos.html I saw that >> REST API allows to call these algorithms: >> >> - Find all shortest paths >> - Find one of the shortest paths between nodes >> - Execute a Dijkstra algorithm with similar weights on relationships >> - Execute a Dijkstra algorithm with weights on relationships >> >> >> The second question is: can't I invoke the A* algorithm by REST API? This >> is related to the fact that I'ld love to have one (ore more) dedicated >> machine to neo4j and access to them by REST API (is this a good solution?) >> >> The last question regards neo4j performance. In my real scenario i may >> import an OSM file of an whole italian region (maybe also the full Italy); >> in the case of one region I can have around 10 millions of nodes (also more >> than 10 million) and some millions of relationship. In this case...what are >> performances with the built-in algorithms Dijkstra and/or A* when i want >> the shortest path (or all paths) between two points located at the end of >> the graph? >> >> Thank you >> Angelo >> > -- You received this message because you are subscribed to the Google Groups "Neo4j" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
