[R] Variogram with Gstat

[ONKELINX, Thierry]

Have a look at the examples in the helpfile for variogram from the gstat
package.

data(meuse)
# no trend:
coordinates(meuse) = ~x+y
variogram(log(zinc)~1, meuse)
# residual variogram w.r.t. a linear trend:
variogram(log(zinc)~x+y, meuse)
# directional variogram:
variogram(log(zinc)~x+y, meuse, alpha=c(0,45,90,135))

# GLS residual variogram:
v = variogram(log(zinc)~x+y, meuse)
v.fit = fit.variogram(v, vgm(1, "Sph", 700, 1))
v.fit
set = list(gls=1)
v
g = gstat(NULL, "log-zinc", log(zinc)~x+y, meuse, model=v.fit, set =
set)
variogram(g)

if (require(rgdal)) {
  proj4string(meuse) = CRS("+init=epsg:28992")
  meuse.ll = spTransform(meuse, CRS("+proj=longlat"))
# variogram of unprojected data, using great-circle distances, returning
km as units
  variogram(log(zinc) ~ 1, meuse.ll)
}

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 giuseppeform at libero.it
Verzonden: dinsdag 24 maart 2009 12:45
Aan: r-help at r-project.org
Onderwerp: [R] Variogram with Gstat

Dear all can you help me? i have this problem: i have a dataset in a
text file 
in a matrix of 3 columns: x, y, z where x and y are the coordinates and
Z are 
the mesurements. How  can i do a variogram with R?

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