On Sun, Apr 15, 2018 at 8:48 PM, Veronica Andreo <veroand...@gmail.com> wrote: > Hi devs, > > I just found something odd. I have a CHIRPS tif for Africa [0], but I would > only need to import Ghana, so I used r.in.gdal -r. However when I visualize > the data, most of it is nodata, while the full map of Africa has data all > over the continent. Then, I tried also with r.import extent=region. Same > result. The only thing providing what I expected to be the right result (a > subset from the full map) is importing the whole map and then using > r.mapcalc to clip (i need the space in my hard disk) > > These are the commands and r.univar output and I attach a screenshot with > the visual results: > > # import ghana boundaries from GADM > v.import input=GHA_adm0.shp output=GHA_adm0 > g.region vector=GHA_adm0 > > # import full map > r.in.gdal in=Desktop/chirps-v2.0.2003.01.01.tif out=chirps_full > > # import subsets > r.in.gdal -r in=chirps-v2.0.2003.01.01.tif out=chirps_ghana1 > r.import in=chirps-v2.0.2003.01.01.tif out=chirps_ghana2 extent=region
... here r.null is missing, like r.null chirps_whatever setnull=-9999 # check with r.univar -e chirps_whatever > # subset imported full map > r.mapcalc expression="chirps_ghana3 = chirps_full" > > ### r.univar outputs > > r.univar chirps_ghana1 > > n: 12052 > minimum: -9999 ^-- this is the hint that r.null is needed In my test I then got r.univar -e chirps_v2_0_2017_01_09 100% total null and non-null cells: 2400000 total null cells: 1181279 Of the non-null cells: ---------------------- n: 1218721 minimum: 0 maximum: 195.447 range: 195.447 mean: 1.41408 mean of absolute values: 1.41408 standard deviation: 5.044 variance: 25.4419 variation coefficient: 356.698 % sum: 1723369.67863694 1st quartile: 0 median (odd number of cells): 0 3rd quartile: 0 90th percentile: 3.99494 which looks AFAIK reasonable (also graphically) HTH markusN _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-dev