On Wednesday 26 August 2009, Emilio Mayorga wrote: > Jose, > > Thanks for your pointer to your web site. Looks like you have some > very interesting and useful code there. I've been trying to do > something similar, though I use raster "zone" grids rather than vector > layers; I'd be happy to share that code, but it's too messy at this > point. I'll write a blog post about it eventually. Having Python > functionality that replicates "zonalstats" would be great, with > histogram extractions thrown in. > > Dylan, Starspan has always looked very promising, but last time I > checked it looked abandoned. When I tried to use it over a year ago, > it choked on my shapefiles and said they had many invalid geometries > (it had been exported from an arc coverage using the old command-line > ArcInfo), so I gave up after trying to identify the problems. Still, > having Starspan functionality within Python would be great.
Hi Emilio, Indeed. The current (C++) version of Starspan is more or less unsupported. I tend to use an older, stabler, version-- but have become frustrated with it in recent studies. I think that the current maintainer Jon Greenberg is working on an R implementation-- however I am not certain that this will scale well to very large rasters. A Python incantation would be more flexible than the current C++ version, but perhaps at a speed cost. The current version is blazing fast, but there aren't any C++ programmers working on it now. If there is sufficient interest, I would like to get it into OSGeo so that a more skilled programmer (than myself) can have a look at it. If you are doing raster-on-raster zonal stats, then GRASS is fairly good at that too. Cheers, Dylan > Cheers, > > -Emilio Mayorga > Applied Physics Laboratory > University of Washington > Box 355640 > Seattle, WA 98105-6698 USA > http://staff.washington.edu/emiliom/ > > On Wed, Aug 26, 2009 at 7:13 AM, Jose Gomez-Dans<jgomezd...@gmail.com> wrote: > > Hi, > > > > 2009/8/20 questions anon <questions.a...@gmail.com> > > > >> Can anyone get me started on a script that can - > >> > >> -Open a shapefile > >> > >> -Open many rasters > >> > >> -Calculate the mean and standard deviation of those rasters within the > >> shapefile region, but is able to ignore areas of zeros or NoData > >> > >> -Output the mean and standard deviation to a table > > > > i've done a similar example to what you want here: > > < > > http://sites.google.com/site/spatialpython/aggregating-data-to-grid-cells > >> Only difference is that I calculate the histogram, rather than just the > > mean and std dev. It is trivial to modify this for your own purposes. In > > fact, when I get some time, I'll throw in a full "zonal stats" class, but > > for now this should get you started. > > > > J > > > > _______________________________________________ > > gdal-dev mailing list > > gdal-dev@lists.osgeo.org > > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
