[postgis-users] Creating a Flow Diagram
aanderson at amherst.edu
Sun Jun 8 19:25:56 PDT 2008
On Jun 8, 2008, at 5:14 PM, Bob Pawley wrote:
> I 'm playing with a variation of the st_translate function we were
> discussing last week.
> I have created two boxes (spatial_ref) and I wish to place an entity
> (graphics.process_dgm) into the temp_ table with the coordinates
> that centers the entity in a specific one of these boxes.
> Here's the code that I have come up with but so far it produces 0
> Insert into temp_ (the_geom)
> Select st_translate(st_translate (graphics.process_dgm.the_geom,
> st_y (st_centroid(graphics.process_dgm.the_geom)) - st_x
> (st_centroid (spatial_ref.the_geom)),
The first function here should be "st_x", not "st_y".
> st_y (st_centroid(graphics.process_dgm.the_geom)) - st_y
> (st_centroid (spatial_ref.the_geom))),
> ( st_xmax(graphics.process_dgm.the_geom) -
> ( st_ymax(graphics.process_dgm.the_geom) -
I don't see anything wrong with this, but you should be able to make a
single st_translate call here since max - min won't change in a
(st_y (st_centroid(graphics.process_dgm.the_geom)) - st_x (st_centroid
(spatial_ref.the_geom))) + ( st_xmax(graphics.process_dgm.the_geom) -
So after matching the centroids you're trying to move the lower left
corner of the bounding box to its upper right corner?
> from graphics.process_dgm, spatial_ref, temp_
I don't think you need the ", temp_", but it probably doesn't hurt.
> where graphics.process_dgm.description = 'Tank'
> and spatial_ref.position_ = '2';
Is spatial_ref.position_ text? If it's an integer, drop the quotes.
More information about the postgis-users