[postgis-users] Cut Shapefiles At A Border

[Paragon Corporation]

Use ST_Intersection In conjunction with ST_Intersects.  ST_Intersection will
clip the geometries so what is left is what falls inside both geometries.

So something like

SELECT i.gid, ST_Intersection(country.the_geom, i.the_geom)
FROM country INNER JOIN someothertable i ON ST_Intersects(country.the_geom,
i.the_geom)

For your countries that are  linestrings, you will need to convert them to
polygons with something like ST_BuildArea.
http://postgis.refractions.net/documentation/manual-svn/ST_BuildArea.html

Hope that helps,
Regina 

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Dan
Blomberg
Sent: Sunday, September 28, 2008 1:54 AM
To: PostGIS Users Discussion
Subject: [postgis-users] Cut Shapefiles At A Border

Hi,

I need to be able to cut shapefiles at a given border.  I have a bunch of
data for the entire country or an area but I want it to be cut at the border
of the state.  I have the state as either a line or an area.

I saw a previous "thread" here and someone said OpenJump could do this.  
I downloaded it and used touching, is_within, etc and it selected them but
it wouldn't cut at the border so I still had polygons that continued for
miles. Is there a way with PostGIS or some other program to cut/trim a
series of shapefiles at a border (line) or once they are outside of an area.

Any help would be greatly appreciated.

Dan
http://www.gpsfiledepot.com
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