[postgis-users] Center of Points Collection

[Paul Ramsey]

Very nice approach.

Select ST_MakePoint(avg(ST_X(point_teom)), avg(ST_Y(point_geom))) FROM
pb_statistics WHERE pg_debit =1;



On Mon, Sep 14, 2009 at 1:03 PM, Rick <graham.rick at gmail.com> wrote:
> It occurs to me that, depending on what you want, you might try averaging
> the points to get a median, since you don't have a shape, and thus no
> concept of area to produce a centroid.
>
> i.e. add them all up and divide by the number of points.
>
> On Mon, Sep 14, 2009 at 3:28 PM, Paul Ramsey <pramsey at cleverelephant.ca>
> wrote:
>>
>> Faster than creating a multipoint is to recognize that ST_Centroid()
>> is just going to return the center of the bbox of the collection
>> anyways, so you can replace it with.
>>
>> SELECT ST_Centroid(ST_Extent(point_geom)) FROM pb_statistics WHERE
>> pg_debit =1;
>>
>> If you want to do it the hard way, then:
>>
>> SELECT ST_Centroid(ST_Collect(point_geom)) FROM pb_statistics WHERE
>> pg_debit =1;
>>
>> P.
>>
>> On Mon, Sep 14, 2009 at 12:24 PM, Dustin Butler <dustin at intrcomm.net>
>> wrote:
>> > Hello,
>> >
>> > Trying to figure out how to find center using a collection of points.
>> >  For
>> > example something like this which doesn't work but you get the idea.
>> >
>> > SELECT ST_AsText(ST_Centriod(SELECT point_geom FROM pb.pb_statistics
>> > WHERE
>> > pb_debit=1));
>> >
>> > I think I need to make a multipoint geom out of the points and pass that
>> > but
>> > haven't figure out yet.
>> >
>> > Thanks,
>> > Dustin Butler
>> > Intrcomm Technology
>> >
>> > Skype: dustinbutler
>> > _______________________________________________
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>> >
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>
>
>
> --
> Cheers!
> Rick
>
>
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