Hi Craig, Any idea how to implement the knn in efficient way? We need to specify an initial distance and if we do not find k neighbours within that distance we need to increase it, which does not seem like very efficient approach.
Thanks, Alireza On Tuesday, September 23, 2014 8:17:04 PM UTC+2, Craig Taverner wrote: > > I did not answer everything. But the JTS distance method will work for all > geometries, so that answers most of your questions. > > The GeoPipeline methods also provide ways to find objects within distances > of other objects (using the rtree for optimized searches). And it provides > sorting too, so you can, for example, search for everything within some > maximum bounds, sort by distance and pick the closest 'k' elements. > > On Tue, Sep 23, 2014 at 8:14 PM, Craig Taverner <cr...@amanzi.com > <javascript:>> wrote: > >> The distance is calculated best using JTS. For example: >> double distance = pointA.distance(pointB) >> >> See >> http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/geom/Geometry.html#distance(com.vividsolutions.jts.geom.Geometry) >> >> On Tue, Sep 23, 2014 at 3:26 PM, Alireza Rezaei Mahdiraji < >> alire...@gmail.com <javascript:>> wrote: >> >>> >>> Hi All, >>> >>> Given two geometries how do compute the distance between >>> them in neo4j spatial? For instance given two points stored in two nodes? >>> >>> What other kind of distance are defined? For instance, is it possible to >>> find >>> distance between a point and a linestring/polygon or distance between >>> two polygons? >>> >>> Related to the concept of distance, it is possible to find objects >>> within a given distance of a >>> given object. But what about computing knn, i.e., finding k elements >>> which are closets to the >>> given object? Shall we compute all distances and then pick top k or >>> there is implemented >>> and optimized way to do this? >>> >>> Thanks, >>> Best, >>> Alireza >>> >>> -- >>> 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 neo4j+un...@googlegroups.com <javascript:>. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> > -- 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 neo4j+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
