How to subset a spatial grid?
Yong, I would have loved to see your R shaking. This argument has been heard more often here. When processing massive grids, please have a look at the function getRasterData in package rgdal. It allows you to _read_ only portions of a grid. -- Edzer
Yong Li wrote:
Thanks Edzer and Hengl. It works. But R is really shaking when large grids are processed. We wish there is improvement of sp in the future like GIS handling grids. Regards Yong ------------------------------------------------------------------------ *From:* Edzer Pebesma [mailto:edzer.pebesma at uni-muenster.de] *Sent:* Tue 20/05/2008 6:11 PM *To:* Yong Li *Cc:* r-sig-geo at stat.math.ethz.ch *Subject:* Re: [R-sig-Geo] How to subset a spatial grid? Have you tried Map1 <- Map[1:100,1:100] ? Note that this works differently for SpatialGridDataFrames and SpatialPixelsDataFrames; the first knows about [rows,cols,bands], the second about [pixels, bands]. -- Edzer Yong Li wrote:
Dear All,
I want to subset a large spatial grid (2000*2000) into many smaller
grids for further processing in my simulation models. Could anyone do it
before and any tips will be highly appreciated?
Library(rgdal)
Map <- readGDAL("yong.img") # one image from erdras imagine
Map$va <- Map$band1
Map$band1 <- NULL
????
Map1 <- a subset of Map$va based on selected cols and rows.
????......
Cheers
Yong Li
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