[R-sig-Geo] question about simulating patchy landscapes
Dylan Beaudette
dylan.beaudette at gmail.com
Fri Oct 3 19:42:28 CEST 2008
On Thursday 25 September 2008, Edzer Pebesma wrote:
> demo(uisim)
This seems work work with the demo code, but not with another example using my
own data:
# setup
library(gstat)
library(spgrass6)
# load GRASS region settings
G <- gmeta6()
grd <- gmeta2grd()
# make a new grid from GRASS region
new_data <- SpatialGrid(grd)
# works fine:
var.model <- vgm(psill=10, model="Exp", range=1000)
sim <- predict(gstat(formula=z~1, dummy=TRUE, beta=0, model=var.model,
nmax=20), newdata = new_data, nsim = 1)
# does not work -- produces a field of '0' values
sim <- predict(gstat(formula=z~1, dummy=TRUE, beta=0, model=var.model,
nmax=20), newdata = new_data, nsim = 1, indicators=TRUE)
# any ideas on why UISIM works in the demo, and not in my examples? I have
noticed that the syntax is slightly different in the demo, could this be the
cause:
# prediction grid:
data(meuse.grid)
gridded(meuse.grid) = ~x+y
# define variable as dummy data
v = vgm(.25, "Sph", 900)
g = gstat(NULL, "var1", x~1, beta = .5, nmax = 20, model = v, dummy = TRUE)
# simulation of a single variable
out = predict(g, meuse.grid, nsim = 20, indicators = TRUE)
Thanks,
Dylan
--
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341
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