[postgis-users] "summing" (polygon, float) pairs

[Obe, Regina]

Reid,

I assume
1) You don't care if polygons are reused to form your new sets 
2) You don't care how many polygons are in each set.  
3) You also are not looking for all possible permutations - just a
random set of answers that solve your equation?



-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Reid
Priedhorsky
Sent: Wednesday, October 01, 2008 6:35 PM
To: PostGIS Users Discussion
Subject: [postgis-users] "summing" (polygon, float) pairs

Dear all,

I have a set of polygons. Associated with each polygon is a number; call

it score. Each polygon can intersect with zero or more other polygons.

What I would like to compute is a set of non-intersecting polygons with 
summed scores -- each of these polygons would be a set of points where 
the sum of all the original polygons' scores covered by the result 
polygon are equal.

Here's an example in one dimension:

Input:

----3------
      ----1----
         ----4----
                     ----2----

Output:

--3--
      -4-
         -8-
            -5-
               -4-
                     ----2-----

It is OK if two adjacent result polygons have equal sums.

Can this be done in PostGIS?

Reid

p.s. thanks for the help on my question a few days ago! I felt a tad 
foolish after learning it was just a missing isvalid() constraint. I 
thought I had one but didn't look carefully enough.
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