Posts

Showing posts from May 16, 2010

numpy + GDAL = agoodle

It's been a while since I've posted anything geo-related. Just want to let folks know about agoodle a project that makes it easy to access raster geo files as numpy arrays (thanks to GDAL), and to query them with polygons. The simplest way to see it in action is to go to landsummary, a project Josh Livni and I worked on a couple years ago, and query the map with a polygon (click "Draw Polygon" on the right side of the map first). Then you'll see a nice summary and a pie-chart (due to some google-chart-api usage by Josh) of the land-use types in the polygon you queried. The backend of that is agoodle. The map is, of course, openlayers.

You can see the usage on the github page but basically, it'll be something like: which gives you a dictionary of raster grid code keys to the area values-- meaning, for each landclass, it tells you the sum area of cells of that class that fall inside the polygon. Note that summarize_wkt can also take keyword arguments for raster_…