Calculate Semi-Variogram for a corExp Object

DESCRIPTION:

This method function calculates the semi-variogram values corresponding to the Exponential correlation model, using the estimated coefficients corresponding to object, at the distances defined by distance.

USAGE:

Variogram(object, distance, sig2, length.out) 

REQUIRED ARGUMENTS:

object
an object inheriting from class corExp, representing an exponential spatial correlation structure.

OPTIONAL ARGUMENTS:

distance
an optional numeric vector with the distances at which the semi-variogram is to be calculated. Defaults to NULL, in which case a sequence of length length.out between the minimum and maximum values of getCovariate(object) is used.
sig2
an optional numeric value representing the process variance. Defaults to 1.
length.out
an optional integer specifying the length of the sequence of distances to be used for calculating the semi-variogram, when distance = NULL. Defaults to 50.

VALUE:

a data frame with columns variog and dist representing, respectively, the semi-variogram values and the corresponding distances. The returned value inherits from class Variogram.

REFERENCES:

Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.

SEE ALSO:

,

EXAMPLES:

cs1 <- corExp(3, form = ~ Time | Rat) 
cs1 <- initialize(cs1, BodyWeight) 
Variogram(cs1)[1:10,]