Re: [Neo4j] Cypher error in neo4j-spatial
Fixed in spatial, Thanks! Sent from my phone. On Jul 3, 2011 7:39 AM, "Andres Taylor" wrote: > We decided that we needed a meta-data character that wasn't ":". Instead, > you now write: "r~TYPE" > > Andrés > > On Sun, Jul 3, 2011 at 12:44 AM, Peter Neubauer wrote: > >> Just pinged Andres on this. The r:TYPE is the culprit. >> >> Sent from my phone. >> On Jul 3, 2011 12:06 AM, "Craig Taverner" wrote: >> > Hi, >> > >> > Recent builds of Neo4j-Spatial no longer like Peters new bounding box >> query. >> > Peter is on vacation, and I am not familiar with the code (nor cypher), >> so >> I >> > thought I would just dump the error message here for now in case someone >> can >> > give me a quick pointer. >> > >> > The line of code is: >> > Query query = parser.parse( "start n=(layer1,'bbox:[15.0, 16.0, 56.0, >> > 57.0]') match (n) -[r] - (x) return n.bbox, r:TYPE, x.layer?, x.bbox?" ); >> > >> > The error is: >> > org.neo4j.cypher.SyntaxError: string matching regex `\z' expected but `:' >> > found >> > at org.neo4j.cypher.parser.CypherParser.parse(CypherParser.scala:75) >> > at org.neo4j.cypher.javacompat.CypherParser.parse(CypherParser.java:39) >> > at >> > >> >> org.neo4j.gis.spatial.IndexProviderTest.testNodeIndex(IndexProviderTest.java:91) >> > >> > Regards, Craig >> > ___ >> > Neo4j mailing list >> > User@lists.neo4j.org >> > https://lists.neo4j.org/mailman/listinfo/user >> ___ >> Neo4j mailing list >> User@lists.neo4j.org >> https://lists.neo4j.org/mailman/listinfo/user >> > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] reify links with other neo4j databases located on different distributed servers
Thanks a lot Rick can you please provide more details on issues which you faced while using this approach and share some code with us . Had you decided about this at design time itself and designed your graph db schema accordingly? Is there much perceived performance penalties if there are a large number of such references spanning physical boundaries? On 7/2/11, Rick Bullotta wrote: > We are using node-id property references (the node id as a property), > qualified with a "logical server" reference, to provide this type of binding > across graphs. If you combine these with an index, you can actually get a > lot of the functionality of relationships "cross graph", spanning physical > boundaries. Of course, as Craig points out, this all has to be done at the > application level, including dealing with cascading deletes when a node is > removed from one graph, ensuring that references to it in another graph are > removed/redirected. > > -Original Message- > From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On > Behalf Of Craig Taverner > Sent: Saturday, July 02, 2011 6:03 AM > To: Neo4j user discussions > Subject: Re: [Neo4j] reify links with other neo4j databases located on > different distributed servers > > As far as I know there is no internal support for transparent traversals > across shards. Generally people are doing that in the application layer. > However, I think there might be a middle ground of sorts. I we modify the > relationship expander, I could imagine that relationships that are between > shards could be modified to return node on the other shard. This would make > the traversal return nodes across shards, but since I've not tried this > myself, I am uncertain if there are other consequences. > > On Sat, Jul 2, 2011 at 4:03 AM, Aliabbas Petiwala > wrote: > >> Hi, >> >> I cannot figure out how my application logic can reify links with >> other neo4j databases located on different distributed servers? >> hence , how can i make the traversals and graph algorithms transparent >> to the location of the different databases ? >> -- >> Aliabbas Petiwala >> M.Tech CSE >> ___ >> Neo4j mailing list >> User@lists.neo4j.org >> https://lists.neo4j.org/mailman/listinfo/user >> > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > -- Aliabbas Petiwala M.Tech CSE ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] Cypher error in neo4j-spatial
We decided that we needed a meta-data character that wasn't ":". Instead, you now write: "r~TYPE" Andrés On Sun, Jul 3, 2011 at 12:44 AM, Peter Neubauer wrote: > Just pinged Andres on this. The r:TYPE is the culprit. > > Sent from my phone. > On Jul 3, 2011 12:06 AM, "Craig Taverner" wrote: > > Hi, > > > > Recent builds of Neo4j-Spatial no longer like Peters new bounding box > query. > > Peter is on vacation, and I am not familiar with the code (nor cypher), > so > I > > thought I would just dump the error message here for now in case someone > can > > give me a quick pointer. > > > > The line of code is: > > Query query = parser.parse( "start n=(layer1,'bbox:[15.0, 16.0, 56.0, > > 57.0]') match (n) -[r] - (x) return n.bbox, r:TYPE, x.layer?, x.bbox?" ); > > > > The error is: > > org.neo4j.cypher.SyntaxError: string matching regex `\z' expected but `:' > > found > > at org.neo4j.cypher.parser.CypherParser.parse(CypherParser.scala:75) > > at org.neo4j.cypher.javacompat.CypherParser.parse(CypherParser.java:39) > > at > > > > org.neo4j.gis.spatial.IndexProviderTest.testNodeIndex(IndexProviderTest.java:91) > > > > Regards, Craig > > ___ > > Neo4j mailing list > > User@lists.neo4j.org > > https://lists.neo4j.org/mailman/listinfo/user > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] Cypher error in neo4j-spatial
Just pinged Andres on this. The r:TYPE is the culprit. Sent from my phone. On Jul 3, 2011 12:06 AM, "Craig Taverner" wrote: > Hi, > > Recent builds of Neo4j-Spatial no longer like Peters new bounding box query. > Peter is on vacation, and I am not familiar with the code (nor cypher), so I > thought I would just dump the error message here for now in case someone can > give me a quick pointer. > > The line of code is: > Query query = parser.parse( "start n=(layer1,'bbox:[15.0, 16.0, 56.0, > 57.0]') match (n) -[r] - (x) return n.bbox, r:TYPE, x.layer?, x.bbox?" ); > > The error is: > org.neo4j.cypher.SyntaxError: string matching regex `\z' expected but `:' > found > at org.neo4j.cypher.parser.CypherParser.parse(CypherParser.scala:75) > at org.neo4j.cypher.javacompat.CypherParser.parse(CypherParser.java:39) > at > org.neo4j.gis.spatial.IndexProviderTest.testNodeIndex(IndexProviderTest.java:91) > > Regards, Craig > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
[Neo4j] Cypher error in neo4j-spatial
Hi, Recent builds of Neo4j-Spatial no longer like Peters new bounding box query. Peter is on vacation, and I am not familiar with the code (nor cypher), so I thought I would just dump the error message here for now in case someone can give me a quick pointer. The line of code is: Query query = parser.parse( "start n=(layer1,'bbox:[15.0, 16.0, 56.0, 57.0]') match (n) -[r] - (x) return n.bbox, r:TYPE, x.layer?, x.bbox?" ); The error is: org.neo4j.cypher.SyntaxError: string matching regex `\z' expected but `:' found at org.neo4j.cypher.parser.CypherParser.parse(CypherParser.scala:75) at org.neo4j.cypher.javacompat.CypherParser.parse(CypherParser.java:39) at org.neo4j.gis.spatial.IndexProviderTest.testNodeIndex(IndexProviderTest.java:91) Regards, Craig ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
[Neo4j] Distinct results in Cypher
Is it possible to get distinct results in Cypher? Something like START a=(1) MATCH (a)-[:FOOTYPE]->(b) RETURN DISTINCT b I have a scenario where a single node may be connected multiple times to another node, and I only want that other node to be returned once. I'd hate to have to do this in my client code. If this feature isn't available in Cypher, consider this a feature request. Thanks! -- Josh Adell ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] neo4j spatial bounding box vs. lat/lon
As I understand it, Andreas is working on the much more complex problem of updating OSM geometries. That is more complex because it involves restructuring the connected graph. The case Boris has is much simpler, just modifying the WKT or WKB in the editable layer. In the Java API this is simply to call the GeometryEncoder.encodeGeometry() method, which will modify the geometry in place (ie. replace the old geometry with a new one). However, I do not think it is that simple on the REST interface. I can check, but think we will need a new method for updating geometries. Internally it is trivial to code. So I just added a quick method, called updateGeometryFromWKT, which requires the geometry (in WKT), the existing geometry node-id, and the layer. Give it a try. On Sat, Jul 2, 2011 at 5:10 PM, Peter Neubauer wrote: > Actually, > Andreas Wilhelm is working right now on updating geometries. > > Sent from my phone. > On Jul 2, 2011 5:00 PM, "Boris Kizelshteyn" wrote: > > Wow that's great! I'll try it out asap. This leads to my next question: > how > > do I update the geometry in a layer, rather than add new? What I am > thinking > > of doing is having a multipoint geometery associated with each of my user > > nodes which will represent their location history. My plan is to add the > > geometry to a "world" layer and then associate the returned node with the > > user. How do I then add new points to that connecter node? Can I just > edit > > the wkt and assume the index will update? Or do you have a better > suggestion > > for doing this? I would rather avoid having each point be a seperate node > as > > I am tracking gps data and getting lots of coordinates, it would be many > > thousands of nodes per user. > > > > Many thanks! > > > >> > >> > >> On Sat, Jul 2, 2011 at 6:48 AM, Craig Taverner > wrote: > >> > >>> Hi Boris, > >>> > >>> Ah! You are using the REST API. That changes a lot, since Neo4j Spatial > is > >>> only recently exposed in REST and we do not expose most of the > >>> capabilities > >>> I have discussed in this thread, or indeed in my other answer today. > >>> > >>> I did recently add some REST methods that might work for you, > specifically > >>> the addEditableLayer, which makes a WKB layer, and the > >>> addGeometryWKTToLayer, for adding any kind of Geometry (including > >>> LineString) to the layer. However, these were only added recently, and > I > >>> have no experience using them myself, so consider this very much > prototype > >>> code. From your other question today, can I assume you are having > trouble > >>> making sense of the data coming back? So we need a better way to return > >>> the > >>> results in WKT instead of WKB? One option would be to enhance the > >>> addEditableLayer method to allow the creation of WKT layers instead of > WKB > >>> layers, so the internal representation is more internet friendly. > >>> > >>> I've just added untested support for setting the format to WKT for the > >>> internal representation of the editable layer in the REST interface. > This > >>> is > >>> untested (outside of my usual unit tests, that is), and is only in the > >>> trunk > >>> of neo4j-spatial, but you are welcome to try it out and see what > happens. > >>> > >>> Regards, Craig > >>> > >>> On Fri, Jul 1, 2011 at 5:29 PM, Boris Kizelshteyn > >>> wrote: > >>> > >>> > Hi Craig, > >>> > > >>> > Thanks so much for this reply. It is very insightful. Is it possible > for > >>> me > >>> > to implement the LineString geometries and lookups using REST? > >>> > > >>> > Many thanks! > >>> > > >>> > On Wed, Jun 8, 2011 at 4:58 PM, Craig Taverner > >>> wrote: > >>> > > >>> > > OK. I understand much better what you want now. > >>> > > > >>> > > Your person nodes are not geographic objects, they are persons that > >>> can > >>> > be > >>> > > at many positions and indeed move around. However, the 'path' that > >>> they > >>> > > take > >>> > > is a geographic object and can be placed on the map and analysed > >>> > > geographically. > >>> > > > >>> > > So the question I have is how do you store the path the person > takes? > >>> Is > >>> > > this a bunch of position nodes connected back to that person? Or > >>> perhaps > >>> > a > >>> > > chain of position-(next)->position-(next)->position, etc? However > you > >>> > have > >>> > > stored this in the graph, you can express this as a geographic > object > >>> by > >>> > > implementing the GeometryEncoder interface. See, for example, the 6 > >>> lines > >>> > > of > >>> > > code it takes to traverse a chain of NEXT locations and produce a > >>> > > LineString > >>> > > geometry in the SimpleGraphEncoder at > >>> > > > >>> > > > >>> > > >>> > > https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 > >>> > > > >>> > > < > >>> > > > >>> > > >>> > > https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 > >>> > > >I
Re: [Neo4j] IMPORTANT: Corruption Bug in 1.4 M05
Hi Jim, thanks for reporting anyway. We run some structr instances on the latest milestone, so I'd be interesed in some more details: - Is 1.4 M04 safe? - How can we detect whether corruption occured, and is there a way recover from that? - Is this bug contained in the current SNAPSHOT? Thanks and best regards Axel -- http://structr.org On 02.07.2011 20:46, Jim Webber wrote: > Hi fellow graphistas, > > In testing our upcoming 1.4 GA release, we discovered a subtle bug in our 1.4 > M05 release that can result in database corruption. Under certain > circumstances with clean shutdowns of the database it's possible that freed > IDs will be recycled more than once, meaning that on restart, multiple nodes > may receive the same node ID, corrupting the graph. > > It's still fine to develop against 1.4 M05 to become familiar with the new > features and APIs which will be preserved in the GA release. However we do > not recommend, as with milestones in general, moving into production on the > 1.4 M05 release since data corruption of data is possible. > > We're now busy making sure that the 1.4 GA release is a completely solid - > thanks to you all for being such an awesome and supportive community. > > Jim > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
[Neo4j] IMPORTANT: Corruption Bug in 1.4 M05
Hi fellow graphistas, In testing our upcoming 1.4 GA release, we discovered a subtle bug in our 1.4 M05 release that can result in database corruption. Under certain circumstances with clean shutdowns of the database it's possible that freed IDs will be recycled more than once, meaning that on restart, multiple nodes may receive the same node ID, corrupting the graph. It's still fine to develop against 1.4 M05 to become familiar with the new features and APIs which will be preserved in the GA release. However we do not recommend, as with milestones in general, moving into production on the 1.4 M05 release since data corruption of data is possible. We're now busy making sure that the 1.4 GA release is a completely solid - thanks to you all for being such an awesome and supportive community. Jim ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] Multiple sessions
Everything written to the database with successful transactions is persisted and will be accessible in any following sessions. Just _don't_ think of a GraphDatabaseService instance as a short lived object (like a SQL connection), but instead see it more as your database server which benefits from being long lived... even days, weeks...) 2011/7/1 Vaccaro, Kristen M > Hi, I have a question about sessions in Neo4j. I'm working with the > embedded Java (not as a server) and I can load my data and query it between > transactions without trouble. My question is whether/how it's possible to > shut down my database at the end of a session and then access it in a new > session later. > > Something like first doing: > GraphDatabaseService graphDb = new EmbeddedGraphDatabase( "var/test/base" > ); > ...Add all my data using transactions > graphDb.shutdown(); > > Then later opening a new session and accessing that database and indices > I've already made. Is that possible (I didn't see anything covering that in > the wiki/documentation)? Or will I need to convert to the server version? > Kristen > > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > -- Mattias Persson, [matt...@neotechnology.com] Hacker, Neo Technology www.neotechnology.com ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] neo4j spatial bounding box vs. lat/lon
Actually, Andreas Wilhelm is working right now on updating geometries. Sent from my phone. On Jul 2, 2011 5:00 PM, "Boris Kizelshteyn" wrote: > Wow that's great! I'll try it out asap. This leads to my next question: how > do I update the geometry in a layer, rather than add new? What I am thinking > of doing is having a multipoint geometery associated with each of my user > nodes which will represent their location history. My plan is to add the > geometry to a "world" layer and then associate the returned node with the > user. How do I then add new points to that connecter node? Can I just edit > the wkt and assume the index will update? Or do you have a better suggestion > for doing this? I would rather avoid having each point be a seperate node as > I am tracking gps data and getting lots of coordinates, it would be many > thousands of nodes per user. > > Many thanks! > >> >> >> On Sat, Jul 2, 2011 at 6:48 AM, Craig Taverner wrote: >> >>> Hi Boris, >>> >>> Ah! You are using the REST API. That changes a lot, since Neo4j Spatial is >>> only recently exposed in REST and we do not expose most of the >>> capabilities >>> I have discussed in this thread, or indeed in my other answer today. >>> >>> I did recently add some REST methods that might work for you, specifically >>> the addEditableLayer, which makes a WKB layer, and the >>> addGeometryWKTToLayer, for adding any kind of Geometry (including >>> LineString) to the layer. However, these were only added recently, and I >>> have no experience using them myself, so consider this very much prototype >>> code. From your other question today, can I assume you are having trouble >>> making sense of the data coming back? So we need a better way to return >>> the >>> results in WKT instead of WKB? One option would be to enhance the >>> addEditableLayer method to allow the creation of WKT layers instead of WKB >>> layers, so the internal representation is more internet friendly. >>> >>> I've just added untested support for setting the format to WKT for the >>> internal representation of the editable layer in the REST interface. This >>> is >>> untested (outside of my usual unit tests, that is), and is only in the >>> trunk >>> of neo4j-spatial, but you are welcome to try it out and see what happens. >>> >>> Regards, Craig >>> >>> On Fri, Jul 1, 2011 at 5:29 PM, Boris Kizelshteyn >>> wrote: >>> >>> > Hi Craig, >>> > >>> > Thanks so much for this reply. It is very insightful. Is it possible for >>> me >>> > to implement the LineString geometries and lookups using REST? >>> > >>> > Many thanks! >>> > >>> > On Wed, Jun 8, 2011 at 4:58 PM, Craig Taverner >>> wrote: >>> > >>> > > OK. I understand much better what you want now. >>> > > >>> > > Your person nodes are not geographic objects, they are persons that >>> can >>> > be >>> > > at many positions and indeed move around. However, the 'path' that >>> they >>> > > take >>> > > is a geographic object and can be placed on the map and analysed >>> > > geographically. >>> > > >>> > > So the question I have is how do you store the path the person takes? >>> Is >>> > > this a bunch of position nodes connected back to that person? Or >>> perhaps >>> > a >>> > > chain of position-(next)->position-(next)->position, etc? However you >>> > have >>> > > stored this in the graph, you can express this as a geographic object >>> by >>> > > implementing the GeometryEncoder interface. See, for example, the 6 >>> lines >>> > > of >>> > > code it takes to traverse a chain of NEXT locations and produce a >>> > > LineString >>> > > geometry in the SimpleGraphEncoder at >>> > > >>> > > >>> > >>> https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 >>> > > >>> > > < >>> > > >>> > >>> https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 >>> > > >If >>> > > you do this, you can create a layer that uses your own geometry >>> encoder >>> > (or >>> > > the SimpleGraphEncoder I referenced above, if you use the same graph >>> > > structure) and your own domain model will be expressed as LineString >>> > > geometries and you can perform spatial operations on them. >>> > > >>> > > Alternatively, if your data is more static in nature, and you are >>> > analysing >>> > > only what the person did in the past, and the graph will therefor not >>> > > change, perhaps you do not care to store the locations in the graph, >>> and >>> > > you >>> > > can just import them as a LineString directly into a standard layer. >>> > > >>> > > Whatever route you take, the final action you want to perform is to >>> find >>> > > points near the LineString (path the person took). I do not think the >>> > > bounding box is the right approach for that either. You need to try, >>> for >>> > > example, the method findClosestEdges in the utilities class at >>> > > >>> > > >>> > >>> https://github.com/neo4j/neo4j-spatial/blob/master/
Re: [Neo4j] neo4j spatial bounding box vs. lat/lon
Wow that's great! I'll try it out asap. This leads to my next question: how do I update the geometry in a layer, rather than add new? What I am thinking of doing is having a multipoint geometery associated with each of my user nodes which will represent their location history. My plan is to add the geometry to a "world" layer and then associate the returned node with the user. How do I then add new points to that connecter node? Can I just edit the wkt and assume the index will update? Or do you have a better suggestion for doing this? I would rather avoid having each point be a seperate node as I am tracking gps data and getting lots of coordinates, it would be many thousands of nodes per user. Many thanks! > > > On Sat, Jul 2, 2011 at 6:48 AM, Craig Taverner wrote: > >> Hi Boris, >> >> Ah! You are using the REST API. That changes a lot, since Neo4j Spatial is >> only recently exposed in REST and we do not expose most of the >> capabilities >> I have discussed in this thread, or indeed in my other answer today. >> >> I did recently add some REST methods that might work for you, specifically >> the addEditableLayer, which makes a WKB layer, and the >> addGeometryWKTToLayer, for adding any kind of Geometry (including >> LineString) to the layer. However, these were only added recently, and I >> have no experience using them myself, so consider this very much prototype >> code. From your other question today, can I assume you are having trouble >> making sense of the data coming back? So we need a better way to return >> the >> results in WKT instead of WKB? One option would be to enhance the >> addEditableLayer method to allow the creation of WKT layers instead of WKB >> layers, so the internal representation is more internet friendly. >> >> I've just added untested support for setting the format to WKT for the >> internal representation of the editable layer in the REST interface. This >> is >> untested (outside of my usual unit tests, that is), and is only in the >> trunk >> of neo4j-spatial, but you are welcome to try it out and see what happens. >> >> Regards, Craig >> >> On Fri, Jul 1, 2011 at 5:29 PM, Boris Kizelshteyn >> wrote: >> >> > Hi Craig, >> > >> > Thanks so much for this reply. It is very insightful. Is it possible for >> me >> > to implement the LineString geometries and lookups using REST? >> > >> > Many thanks! >> > >> > On Wed, Jun 8, 2011 at 4:58 PM, Craig Taverner >> wrote: >> > >> > > OK. I understand much better what you want now. >> > > >> > > Your person nodes are not geographic objects, they are persons that >> can >> > be >> > > at many positions and indeed move around. However, the 'path' that >> they >> > > take >> > > is a geographic object and can be placed on the map and analysed >> > > geographically. >> > > >> > > So the question I have is how do you store the path the person takes? >> Is >> > > this a bunch of position nodes connected back to that person? Or >> perhaps >> > a >> > > chain of position-(next)->position-(next)->position, etc? However you >> > have >> > > stored this in the graph, you can express this as a geographic object >> by >> > > implementing the GeometryEncoder interface. See, for example, the 6 >> lines >> > > of >> > > code it takes to traverse a chain of NEXT locations and produce a >> > > LineString >> > > geometry in the SimpleGraphEncoder at >> > > >> > > >> > >> https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 >> > > >> > > < >> > > >> > >> https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 >> > > >If >> > > you do this, you can create a layer that uses your own geometry >> encoder >> > (or >> > > the SimpleGraphEncoder I referenced above, if you use the same graph >> > > structure) and your own domain model will be expressed as LineString >> > > geometries and you can perform spatial operations on them. >> > > >> > > Alternatively, if your data is more static in nature, and you are >> > analysing >> > > only what the person did in the past, and the graph will therefor not >> > > change, perhaps you do not care to store the locations in the graph, >> and >> > > you >> > > can just import them as a LineString directly into a standard layer. >> > > >> > > Whatever route you take, the final action you want to perform is to >> find >> > > points near the LineString (path the person took). I do not think the >> > > bounding box is the right approach for that either. You need to try, >> for >> > > example, the method findClosestEdges in the utilities class at >> > > >> > > >> > >> https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/SpatialTopologyUtils.java#L115 >> > > >> > > < >> > > >> > >> https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/SpatialTopologyUtils.java#L115 >> > > >This >> > > method can find the part of the persons
Re: [Neo4j] reify links with other neo4j databases located on different distributed servers
We are using node-id property references (the node id as a property), qualified with a "logical server" reference, to provide this type of binding across graphs. If you combine these with an index, you can actually get a lot of the functionality of relationships "cross graph", spanning physical boundaries. Of course, as Craig points out, this all has to be done at the application level, including dealing with cascading deletes when a node is removed from one graph, ensuring that references to it in another graph are removed/redirected. -Original Message- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Craig Taverner Sent: Saturday, July 02, 2011 6:03 AM To: Neo4j user discussions Subject: Re: [Neo4j] reify links with other neo4j databases located on different distributed servers As far as I know there is no internal support for transparent traversals across shards. Generally people are doing that in the application layer. However, I think there might be a middle ground of sorts. I we modify the relationship expander, I could imagine that relationships that are between shards could be modified to return node on the other shard. This would make the traversal return nodes across shards, but since I've not tried this myself, I am uncertain if there are other consequences. On Sat, Jul 2, 2011 at 4:03 AM, Aliabbas Petiwala wrote: > Hi, > > I cannot figure out how my application logic can reify links with > other neo4j databases located on different distributed servers? > hence , how can i make the traversals and graph algorithms transparent > to the location of the different databases ? > -- > Aliabbas Petiwala > M.Tech CSE > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] neo4j spatial bounding box vs. lat/lon
Hi Boris, Ah! You are using the REST API. That changes a lot, since Neo4j Spatial is only recently exposed in REST and we do not expose most of the capabilities I have discussed in this thread, or indeed in my other answer today. I did recently add some REST methods that might work for you, specifically the addEditableLayer, which makes a WKB layer, and the addGeometryWKTToLayer, for adding any kind of Geometry (including LineString) to the layer. However, these were only added recently, and I have no experience using them myself, so consider this very much prototype code. From your other question today, can I assume you are having trouble making sense of the data coming back? So we need a better way to return the results in WKT instead of WKB? One option would be to enhance the addEditableLayer method to allow the creation of WKT layers instead of WKB layers, so the internal representation is more internet friendly. I've just added untested support for setting the format to WKT for the internal representation of the editable layer in the REST interface. This is untested (outside of my usual unit tests, that is), and is only in the trunk of neo4j-spatial, but you are welcome to try it out and see what happens. Regards, Craig On Fri, Jul 1, 2011 at 5:29 PM, Boris Kizelshteyn wrote: > Hi Craig, > > Thanks so much for this reply. It is very insightful. Is it possible for me > to implement the LineString geometries and lookups using REST? > > Many thanks! > > On Wed, Jun 8, 2011 at 4:58 PM, Craig Taverner wrote: > > > OK. I understand much better what you want now. > > > > Your person nodes are not geographic objects, they are persons that can > be > > at many positions and indeed move around. However, the 'path' that they > > take > > is a geographic object and can be placed on the map and analysed > > geographically. > > > > So the question I have is how do you store the path the person takes? Is > > this a bunch of position nodes connected back to that person? Or perhaps > a > > chain of position-(next)->position-(next)->position, etc? However you > have > > stored this in the graph, you can express this as a geographic object by > > implementing the GeometryEncoder interface. See, for example, the 6 lines > > of > > code it takes to traverse a chain of NEXT locations and produce a > > LineString > > geometry in the SimpleGraphEncoder at > > > > > https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 > > > > < > > > https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/encoders/SimpleGraphEncoder.java#L82 > > >If > > you do this, you can create a layer that uses your own geometry encoder > (or > > the SimpleGraphEncoder I referenced above, if you use the same graph > > structure) and your own domain model will be expressed as LineString > > geometries and you can perform spatial operations on them. > > > > Alternatively, if your data is more static in nature, and you are > analysing > > only what the person did in the past, and the graph will therefor not > > change, perhaps you do not care to store the locations in the graph, and > > you > > can just import them as a LineString directly into a standard layer. > > > > Whatever route you take, the final action you want to perform is to find > > points near the LineString (path the person took). I do not think the > > bounding box is the right approach for that either. You need to try, for > > example, the method findClosestEdges in the utilities class at > > > > > https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/SpatialTopologyUtils.java#L115 > > > > < > > > https://github.com/neo4j/neo4j-spatial/blob/master/src/main/java/org/neo4j/gis/spatial/SpatialTopologyUtils.java#L115 > > >This > > method can find the part of the persons path that it closest to the point > > of > > interest. There also also many other geographic operations you might be > > interested in trying, once you have a better feel for the types of > queries > > you want to ask. > > > > Regards, Craig > > > > On Wed, Jun 8, 2011 at 2:17 AM, Boris Kizelshteyn > > wrote: > > > > > Thanks for the detailed response! Here is what I'm trying to do and I'm > > > still not sure how to accomplish it: > > > > > > 1. I have a node which is a person > > > > > > 2. I have geo data as that person moves around the world > > > > > > 3. I use the geodata to create a bounding box of where that person has > > been > > > today > > > > > > 4. I want to say, was this person A near location X today? > > > > > > 5. I do this by seeing if location X is in A's bounding box. > > > > > > From looking at what you suggest doing, it's not clear how I assign the > > > node > > > person A to a layer? Is it that the bounding box is now in the layer > and > > > not > > > in the node? The issue then becomes, how od I associate the two as the > > > RTree > > > relationship seems to es
Re: [Neo4j] wkb value in node created by addGeometryWKTToLayer
Hi Boris, You do not need to read the property yourself from the node, rather use the GeometryEncoder for this, it converts from the internal spatial storage to the Geometry class, which you can work with. If you call geom.toString() you will get a nice printable version (in WKT). Using the GeometryEncoder is a particularly good idea because we support many internal storage formats, not just the WKB you found. If you have point data only, you should consider using the SimplePointLayer (created with SpatialDatabaseService.createSimplePointLayer()), which will store the Point as two properties, for latitude and longitude. Back to your main question: WKB and WKT are two different formats for representing spatial data. We support both with the WKBGeometryEncoder and WKTGeometryEncoder classes, but in both cases we convert from that format to JTS Geometry class for performing spatial operations on. Internally these classes use the WKBReader/WKBWriter (and WKT versions of this) for performing the conversions. If you want to convert between WKB and WKT yourself, you should just use the JTS code directly. But as I said before, I do not think you need to do this. If you are getting your nodes from a search using the index, something like search.getResults().get(0).getGeometry().toString() will return the WKT version. Regards, Craig On Sat, Jul 2, 2011 at 1:04 AM, Boris Kizelshteyn wrote: > Craig or anyone who can answer this: what does the wkb value represent > here. > I know its the well known bytes, but how do I get back to wkt? I thought it > was a byte array, but I can't seem to get my original values back. Form the > values in the test case I have: > > POINT(15.2 60.1) > > > wkb: > > [0,0,0,0,2,0,0,0,2,64,46,51,51,51,51,51,51,64,78,25,-103,-103,-103,-103,-102,64,46,-103,-103,-103,-103,-103,-102,64,78,12,-52,-52,-52,-52,-51] > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] reify links with other neo4j databases located on different distributed servers
As far as I know there is no internal support for transparent traversals across shards. Generally people are doing that in the application layer. However, I think there might be a middle ground of sorts. I we modify the relationship expander, I could imagine that relationships that are between shards could be modified to return node on the other shard. This would make the traversal return nodes across shards, but since I've not tried this myself, I am uncertain if there are other consequences. On Sat, Jul 2, 2011 at 4:03 AM, Aliabbas Petiwala wrote: > Hi, > > I cannot figure out how my application logic can reify links with > other neo4j databases located on different distributed servers? > hence , how can i make the traversals and graph algorithms transparent > to the location of the different databases ? > -- > Aliabbas Petiwala > M.Tech CSE > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
Re: [Neo4j] GSoC 2011 Neo4j Geoprocessing | Weekly Report #6
Hi Andreas, Sounds like good progress over all. It is only a week to the mid-terms, so it would be good to do a general code overview and see if this can be integrated with trunk. Shall we plan for a review and test integration in the middle of next week? Regards, Craig On Sat, Jul 2, 2011 at 10:25 AM, Andreas Wilhelm wrote: > Hi, > > This week I had a little blocker with deleting some subgraph nodes and > relations. For that I made a seperate test to identify the problem and > try to find a solution. > > Apart from that I integrated a additonal spatial type function to get > the distance between geometry nodes and > updated the already existing spatial type functions to the new API. > > > Best Regards > > Andreas Wilhelm > ___ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
[Neo4j] GSoC 2011 Neo4j Geoprocessing | Weekly Report #6
Hi, This week I had a little blocker with deleting some subgraph nodes and relations. For that I made a seperate test to identify the problem and try to find a solution. Apart from that I integrated a additonal spatial type function to get the distance between geometry nodes and updated the already existing spatial type functions to the new API. Best Regards Andreas Wilhelm ___ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
