[R] plot two variograms on a same graph

[Paul Hiemstra]

Hi,

It is possible, but without you specifying in which pacakge you are 
going to fit the variograms it is hard for us to provide an example. And 
what do you mean by variogram, is that the sample variogram or the 
fitted variogram model, or both? Try and keep to the posting guide next 
time to make it possible for us to answer your question. When you use 
gstat for geostatistics you can use somehting along the line of 
(assuming that only the variogram model is different):

library(automap)   # I use automap to fit the variogram, available on CRAN
library(lattice)
data(meuse)
coordinates(meuse) = ~x+y

av1 = autofitVariogram(log(zinc)~dist, meuse, model = "Sph")
av2 = autofitVariogram(log(zinc)~dist, meuse, model = "Exp")

# Make the plot
xyplot(gamma ~ dist, av1$exp_var,
    panel = function(...) {
       panel.xyplot(...)

       # First model
       vm1 = av1$var_model
       ret = variogramLine(vm1, maxdist = 1600)
       llines(ret$dist, ret$gamma)

       # Second model
       vm2 = av2$var_model
       ret = variogramLine(vm2, maxdist = 1600)
       llines(ret$dist, ret$gamma, col = "red")
    }
)

cheers,
Paul

ps There is a mailing list for geographical problems, r-sig-geo. These 
kinds of problems are likely to get more response there.

damien landais wrote:
> Hi,
> I would know how to plot two variograms on a same graph. I can plot one by one but I would draw both on the same one.
> Is it possible? Do i need any special package?
>
> Thanks!
>
> Cordialement
> Damien Landais
>
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>   


-- 
Drs. Paul Hiemstra
Department of Physical Geography
Faculty of Geosciences
University of Utrecht
Heidelberglaan 2
P.O. Box 80.115
3508 TC Utrecht
Phone:  +3130 274 3113 Mon-Tue
Phone:  +3130 253 5773 Wed-Fri
http://intamap.geo.uu.nl/~paul