Hi Kevin No; I'm thinking about some query (or function) that selects random points (POIs) with certain characteristics like decreasing density. I didn't find much theory about how to *create* such random points. There seems to be more literature and implementation about measuring geographic distribution (like in ArcGIS http://bit.ly/13lTFj9 ). Under "radial distribution function" I understand a function which describes how density varies depending on the distance from a reference point (= the user). Yours, Stefan 2013/1/10 Kevin Grittner <kgrittn@xxxxxxxx>: > Stefan Keller wrote: > >> "... ORDER BY random() LIMIT 10;" works ok. >> >> But with the following option it gets more tricky assume: >>> And as an option the (limited) resultset should be spatially >>> distributed (not clustered). >> >> I'm thinking about some radial spatial distribution function. > > So, you explicitly *don't* want a random selection? By "spatially > distributed" you mean that if you have already chosen one > particular location, other locations which are close to it should > be less probable (or impossible) to include in the limited result > set? How would you define the desired result? The one with the > highest best solution to the "traveling salesman" problem? > > -Kevin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
