[GRASS-user] finding bounding box of polygons

[Jerry Nelson]

What I'm trying to do is get the bounding boxes around each country in the
world, so I can create a region file for each. This would make doing
graphics by country much easier. For example, we have constructed a raster
at 1 km resolution of the number of amphibian species ranges at each
location for the whole world. There are times when I just want, say the
counts in India. We have a nice little script that generates a png
automatically based on a region file. It would be nice to have such a file
for each country in the world.

If I read your example correctly, ogrinfo gives me the box around the entire
shapefile, not individual polygons. I suppose an alternative would be to
somehow export each country polygon as a separate shapefile and get the
region of that.

Any tips appreciated.
Thanks, Jerry

-----Original Message-----
From: Jose Gomez-Dans [mailto:jgomezdans at gmail.com] 
Sent: Thursday, September 27, 2007 4:59 PM
To: Jerry Nelson
Cc: grassuser at grass.itc.it
Subject: Re: [GRASS-user] finding bounding box of polygons

Hi,

On 9/27/07, Jerry Nelson <gnelson at uiuc.edu> wrote:
> I'd like to construct a list of the bounding box coordinates for all the
> polygons in a vector file. I could find nothing in the manual that seemed
to
> do that. Any tips appreciated.

Not a GRASS-centric response :), but if it is just a box you're after,
you can probably use ogrinfo for this, as it gives you the Extent of
your file. As an example, using it with the world.shp Shapefile
results in:
$ ogrinfo -so python/world.shp world
INFO: Open of `python/world.shp'
      using driver `ESRI Shapefile' successful.

Layer name: world
Geometry: Polygon
Feature Count: 244
Extent: (-180.000000, -89.900000) - (180.000000, 83.674733)
Layer SRS WKT:
(unknown)
NAME: String (40.0)
CAPITAL: String (64.0)
APPROX: Real (15.0)
AREA: Real (20.15)
SOURCETHM: String (16.0)

Hope that helps