Hi Regina,
I am trying to have a UNION of two shapefiles.
shape A has code as attribute
shape B has info as attribute
I wish to have a result where
1. Both the shapes intersected portions will have both the attributes and
2. The portions which donot intersect have their portion represented as well,
with zero as value for the attribute information that is missing.
So the resultant shape AB will have 2 attributes Code and Info and
values as per intersection, or zero values for the attribute that doesnot
intersect.
The resultant will also have corresponding geometries of intersected portions
as polygons gernerated, and unintersected portions also modified as seperate
polygons.
Please give me some lead to find proper SQL query.
Cheers
Ravi Kumar
"Obe, Regina" <[EMAIL PROTECTED]> wrote:
Ravi,
Still not quite clear what question you are trying to answer.
I am guessing that you are getting duplicates because you have a one to many
going on here. But I'm not sure which is the one and which is the many.
Also you don't need coalesce here since that is only useful if you expect one
of your fields to be null. In this case since you are doing an inner join,
neither will be NULL. Or perhaps you don't want to do an inner join.
It might be that you really want to use the aggregate form of geomunion
Something like
SELECT strubuf.struclass, geomunion(geof.geometry) AS geofac
FROM geof INNER JOIN strubuf ON (geof.geometry && strubuf.geometry AND
intersects(strubuf.geometry, geof.geometry))
GROUP BY strubuf.struclass
Just a guess. But perhaps that doesn't answer the question you were trying
to ask.
---------------------------------
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of RAVI KUMAR
Sent: Tuesday, September 11, 2007 6:26 AM
To: [EMAIL PROTECTED]
Cc: postgis
Subject: [postgis-users] UNION
Hi,
I have prepared a course material for training in Jump for Geoscientists.
Added a minerological theme in which the final output results in prospectivity
map.
I have used Post-GIS where ever complex bullion operators are needed. This was
done smoothly.
But Iam now held-up in UNION and Intersection. Jump gives an OVERLAY which
equals intersection. But the problem needs both
Intersected portion and
Non intersecting portion together.
Followed the advise given on this list to get the result. But the result
OPENJUMP
1.Overlay Layers A, B
2. Make union of the result (to use as a mask)
3. A-Union and B-union and combine theses two layers
4. Add Overlay to this.
This does the work but you have duplicate geometries which are filled with
different attributes in different instances.
POSTGIS:
Followinf the suggestions on the Postgis list I have tried this query.
SELECT strubuf.struclass, COALESCE(geomunion(strubuf.geometry,
geof.geometry), geof.geometry) AS geofac FROM geof INNER JOIN strubuf ON
(geof.geometry && strubuf.geometry AND
intersects(strubuf.geometry, geof.geometry));
But this doesnt result in a table geofac
This is where I am..
But for this additional exercise every thing else is ready.
However Proof of Concept for Geoscientists lies in THIS.
Cheers
Ravi Kumar
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