> Jerry Nelson 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. .. > 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.
ogrinfo will give the box around all the data, as will 'v.info -g'. > I suppose an alternative would be to somehow export each country > polygon as a separate shapefile and get the region of that. you could write a bash loop which cycled through all the cat values v.extract MAP=yourmap for CAT in `v.category in=roads op=print | sort -n | uniq` ; do unset north south east west echo "[$CAT]" v.extract in=$MAP out=tmp_map_$$ list=$CAT eval `v.info -g tmp_map_$$` echo "$CAT: n=$north s=$south e=$east w=$west" g.remove tmp_map_$$ done # I forget the better way to do that loop ? I believe a number of vector modules use the polygon bounding boxes internally (see v.in.ogr section of doc/vector/TODO in the source code), so using a SWIG interface to get those directly with a vector library fn would be a lot faster than extracting each with v.extract. For 250 or so countries, the above script shouldn't take too long. Hamish _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
