[R-sig-Geo] How to subset a spatial grid?

[Edzer Pebesma]

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
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo at stat.math.ethz.ch
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >  
>