[GRASS-stats] subset on spatialGrid??

[Roger Bivand]

On Tue, 22 Jan 2008, Jarek Jasiewicz wrote:

> Hi?
>
> subset(spGRID, raster==1) or subset(spGRID, data$raster==1)
> Can I do this or something similar??
>
> i.e I'd like to avoid to convert raster to regular data.frame and use subset 
> on dataf.rame due to long time of conversion

Hi,

There is no guarantee that the output is going to be a full grid, so I 
suggest casting to SpatialPixelsDataFrame first and subsetting that:

library(sp)
data(meuse.grid)
coordinates(meuse.grid) <- c("x", "y")
gridded(meuse.grid) = TRUE
fullgrid(meuse.grid) = TRUE
summary(meuse.grid)
o1 <- as(meuse.grid, "SpatialPixelsDataFrame")
o2 <- o1[o1$ffreq == 1,]
summary(o2)

Hope this helps,

Roger

> tahnx
> Jarek
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no