# [postgis-users] points from st_distance

Stephen Woodbridge woodbri at swoodbridge.com
Wed Feb 11 08:49:51 PST 2009

```Hmmmm, why not do something like:

select *, ST_distance(point, object) as dist from table expand(point,
min_distance) && object and dist <= min_distance order by dist limit 1;

-Steve

Paragon Corporation wrote:
>
> Nicklas,
>
> You are correct there is no function for doing this.  We have on
> occasion needed to do this ourselves and what we usually do is
>
> 1) first find the minimum distance
> 2) figure out which point/pointset on the geometry satisfies the minimum
> distance using buffer and intersection (with minimum distance being the
> buffer distance).
>
> I think I have the code lying around here somewhere.
>
> As far as ST_Distance goes.  Haven't looked at the code that closely,
> but it does some sort of recursive call and there could be more than one
> point that satisfies the condition and it only cares about the first one
> it comes across so such a thing may or may not be quite what you are
> looking for.
>
> Hope that helps,
> Regina
>
>
>
> *From:* postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] *On Behalf Of
> *nicklas.aven at jordogskog.no
> *Sent:* Wednesday, February 11, 2009 4:47 AM
> *To:* postgis-users at postgis.refractions.net
> *Subject:* [postgis-users] points from st_distance
>
> Hallo
>
> I have a question or suggestion.
>
> If I have missed some functionality please tell me.
>
> The thing is I have often needed information about from which points the
> distance in st_distance is calculated.
> I mean, somewhere in the function the information have to be. Would it
> be possible to build a new function which
> returned the distance, startpoint, endpoint as array or something like that.
>
> Am I right about that this functionality is missing and
> am I right about that the points have to be identified somewhere in the
> function and that it ought to be possible to present them in a function.
>
> If I'm right so far I would like to come this as a suggestion.
>
> I also have to thank you all for postgis.
> It has been a very nice experience to start handling the gis analysing
> and processing in database-environment.
> My next step is to try to manage any of the procedural languages. Then I
> guess I can do just anything with all the points and polygons out there :-).
>
> /Nicklas
>
>
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