[postgis-users] Efficient Way To Get Voronoi Polygons and Matched Points

[Tom van Tilburg]

Hi Gerard,

Considering that your points will always be in the heart of your polygons,
an ST_Intersects would be faster than ST_Within. 1000 points x 1000
polygons should not be a problem at all in this matter, but you might
consider adding a spatial index to the polygons.
On a side note: if your GUI is a web-site, you may consider using D3
voronoi: https://github.com/d3/d3-voronoi It does exactly what you describe.

Best,
  Tom

On Thu, 2 Mar 2017 at 04:28 Gerard LYNCH <gerard.lynch at ericsson.com> wrote:

> Hello,
>
>
>
> I'm using postgis2.3 and ST_VoronoiPolygons.
>
>
>
> I would like to know the best way to do a reverse lookup of sorts to find
> out which Voronoi polygon maps to which point(s) used in ST_Collect.
>
>
>
> Currently I'm looping through each of the input points and doing a
> ST_Within on each of the Voronoi polygons until I get a match. This can be
> time consuming when there are 1000 points and 1000 voronoi polygons. I
> could also do the reverse and loop through each of the Voronoi polygons and
> fetch points within the polygon but I am wondering if there is a more
> efficient approach.
>
>
>
> Ideally an object that returned something like "Polygon1 => [pointa,
> pointb], Polygon2 => [pointc]" etc would be preferable.
>
>
>
> My use case is when someone clicks on a Voronoi polygon in my GUI I would
> like to be able to provide the user with information on the points used to
> create that polygon.
>
>
>
> Cheers,
>
> Gerard
>
>
>
>
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