[GRASS-user] calculating statistics based upon a raster patch map
Hi list, I've got two maps, a map with patches or areas which I want to evaluate. A second map contains a parameter which I want to evaluate (average, std) based upon areas as delineated in the first map. The output of all this would optimally be a third map with the results of the evaluation (average, std) given to the areas of the first map. Is this possible in a simple way, or should I write something myself. I can't seem to find a premade function that does this or something close to it. Kind regards, Koen ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] calculating statistics based upon a raster patch map
On Donnerstag, 20. November 2008 13:57:42 Hufkens Koen wrote: Hi list, I've got two maps, a map with patches or areas which I want to evaluate. A second map contains a parameter which I want to evaluate (average, std) based upon areas as delineated in the first map. The output of all this would optimally be a third map with the results of the evaluation (average, std) given to the areas of the first map. Is this possible in a simple way, or should I write something myself. I can't seem to find a premade function that does this or something close to it. it is quit simple: 1) change your 'patch map' with r.to.vect and v.to.rast into individually numbered patches 2) change your value_raster to integer and multiplication (e.g. '*100') is advisable: r.mapcalc tmp1=int(value_raster*100) 3) query your raster: r.statistics base=patch_raster cover=tmp1 method=average out=value_raster --o 4) perhaps use r.mapcalc to revert the *100 modification in the new map regards, Martin -- ** University of Wuerzburg Institute of Geography Department of Remote Sensing Remote Sensing and Biodiversity Unit Am Hubland 97074 Wuerzburg, Germany @ German Aerospace Center (DLR) German Remote Sensing Data Center (DFD) Phone: +49-(0)931-888-4797 Fax:+49-(0)931-888-4961 Email: [EMAIL PROTECTED] url: http://www.remote-sensing.uni-wuerzburg.de ** ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] calculating statistics based upon a raster patch map
Hufkens Koen wrote: I've got two maps, a map with patches or areas which I want to evaluate. A second map contains a parameter which I want to evaluate (average, std) based upon areas as delineated in the first map. The output of all this would optimally be a third map with the results of the evaluation (average, std) given to the areas of the first map. Is this possible in a simple way, or should I write something myself. I can't seem to find a premade function that does this or something close to it. r.statistics does this, but both inputs have to be integer raster maps. In 7.0-svn, r.statistics2 and r.statistics3 provide similar functionality, but allow the cover map to be floating-point. If your base map is a vector map, you can convert it with v.to.rast. If you need aggregates other than those provided by r.statistics etc, then you can to use r.stats (with the restriction that both maps must be integers) to collate the data into tuples of (base category, cover value, count), and calculate the aggregates with e.g. awk. -- Glynn Clements [EMAIL PROTECTED] ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
