[postgis-users] [GENERAL] Query with LIMIT but as random result set?

[Stefan Keller]

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 at mail.com>:
> 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