gstat (version 0.9-22)

vgm: Generate, or Add to Variogram Model

Description

Generates a variogram model, or adds to an existing model. print.variogramModel prints the essence of a variogram model.

Usage

vgm(psill, model, range, nugget, add.to, anis, kappa = 0.5, ..., covtable)
print.variogramModel(x, ...)

Arguments

psill

(partial) sill of the variogram model component

model

model type, e.g. "Exp", "Sph", "Gau", "Mat". Calling vgm() without a model argument returns a data.frame with available models.

range

range of the variogram model component

kappa

smoothness parameter for the Matern class of variogram models

nugget

nugget component of the variogram (this basically adds a nugget compontent to the model)

add.to

a variogram model to which we want to add a component

anis

anisotropy parameters: see notes below

x

a variogram model to print

...

arguments that will be passed to print, e.g. digits (see examples)

covtable

if model is Tab, instead of model parameters a covariance table can be passed here. See covtable.R in tests (experimental).

Value

• an object of class variogramModel, which extends data.frame.

  When alled without a model argument, a data.frame with available models is returned, having two columns: short (abbreviated names, to be used as model argument: "Exp", "Sph" etc) and long (with some description).

References

Pebesma, E.J., 2004. Multivariable geostatistics in S: the gstat package. Computers & Geosciences, 30: 683-691.

See Also

show.vgms to view the available models, fit.variogram, variogram.line, variogram for the sample variogram.

Examples

vgm()
vgm(10, "Exp", 300)
x <- vgm(10, "Exp", 300)
vgm(10, "Nug", 0)
vgm(10, "Exp", 300, 4.5)
vgm(10, "Mat", 300, 4.5, kappa = 0.7)
vgm( 5, "Exp", 300, add.to = vgm(5, "Exp", 60, nugget = 2.5))
vgm(10, "Exp", 300, anis = c(30, 0.5))
vgm(10, "Exp", 300, anis = c(30, 10, 0, 0.5, 0.3))
# Matern variogram model:
vgm(1, "Mat", 1, kappa=.3)
x <- vgm(0.39527463, "Sph", 953.8942, nugget = 0.06105141)
x
print(x, digits = 3);
# to see all components, do
print.data.frame(x)