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plot two variograms on a same graph

3 messages · damien landais, ONKELINX, Thierry, Paul Hiemstra

Original
damien landais
# 
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
ONKELINX, Thierry
# 
Dear Damien,

I tend do use ggplot2 for more advanced plotting. You only have to
create a dataframe with all the data you need. Here are some examples.

	library(gstat)
	library(ggplot2)
	data(meuse)
	coordinates(meuse) = ~x+y
	g1 <- gstat(id = "Raw", formula = log(zinc)~1, data = meuse)
	g2 <- gstat(id = "Linear trend", formula = log(zinc)~x+y, data =
meuse)
	vg1 <- variogram(g1)
	vg2 <- variogram(g2)
	ggplot(rbind(vg1, vg2), aes(x = dist, y = gamma, colour = id)) +
geom_point()
	
	vgm1 <- fit.variogram(vg1, vgm(1, "Sph", 700, 1))
	vgm2 <- fit.variogram(vg2, vgm(1, "Sph", 700, 1))
	vgLine <- rbind(
		cbind(variogramLine(vgm1, maxdist = max(vg1$dist)), id =
"Raw"),
		cbind(variogramLine(vgm2, maxdist = max(vg2$dist)), id =
"Linear trend")
	)
	ggplot(rbind(vg1, vg2), aes(x = dist, y = gamma, colour = id)) +
geom_line(data = vgLine) + geom_point()
 
HTH,

Thierry

------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium
tel. + 32 54/436 185
Thierry.Onkelinx at inbo.be
www.inbo.be

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to
say what the experiment died of.
~ Sir Ronald Aylmer Fisher

The plural of anecdote is not data.
~ Roger Brinner

The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of
data.
~ John Tukey

-----Oorspronkelijk bericht-----
Van: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
Namens damien landais
Verzonden: woensdag 10 juni 2009 13:55
Aan: R-help at r-project.org
Onderwerp: [R] plot two variograms on a same graph

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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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: