On Mon, 14 Jun 2010, Leonardo Hardtke wrote:
Hi list,
I'm tryng to do a simple random subset of spatial points in R and don't know
how....
I tried:
library(spgrass6)
hs=readVECT6("hs...@hot_spot") (3500 point) #SpatialPointDataFrame
hs_smpl=spsample(hs, 200, "random") #->SpatialPoints
Why do you thing that this is a subsample of your points? It is a sample
of 200 points in the bounding box of your points, I think. To subsample,
generate a new object by subsetting on row indices in the sample:
library(sp)
data(meuse)
coordinates(meuse) <- c("x", "y")
nrow(meuse)
plot(meuse, axes=TRUE)
plot(spsample(meuse, n=50, type="random"), col="red", add=TRUE)
plot(meuse[sample(x=nrow(meuse), size=50),], col="blue", pch=16, add=TRUE)
Hope this helps,
Roger
the question is... how do I attach the right data?
Thanks!
Leonardo Hardtke
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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: [email protected]
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