On 12.10.2010 20:36 (UTC+1), Barry Rowlingson wrote:
Anybody still reading this?
Yes, even though I am not working with grd data, the problem is
interesting. Instead I am working with .sgrd (SAGA GRID binaries), which
can be read with rgdal and/or RSAGA.
I'm sometimes so stuck with sp-objects and rgdal that I forget that
the easiest way to read raw binary data is with readBin. Wrap it into
a function, make it a matrix, now I can easily read time slices:
readTime<-
function(f,tm,x=69,y=65,size=4,type="double",NAvalue=-999){
c = file(f,open="rb")
seek(c,x*y*(tm-1)*size)
m=matrix(readBin(c,type,x*y,size),x,y)
close(c)
m[abs(m-NAvalue)<.Machine$double.eps] = NA
m
}
par(mfrow=c(2,2))
for(p in 1:4){
image(readTime("rf0.5_1975.grd",p))
}
I didn't realise it was India because my gdal virtual raster was sideways.
Thanks for showing this way for working with binary data,
Rainer Hurling
Barry
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