Calculate Semi-variogram for a corExp Object
Usage
Variogram(object, distance, sig2, length.out)
Arguments
object
|
an object inheriting from class corExp ,
representing an exponential spatial correlation structure.
|
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 .
|
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
.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
.Author(s)
Jose Pinheiro and Douglas BatesReferences
Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.See Also
corExp
, plot.Variogram
Examples
library(lme)
library(mva)
data(BodyWeight)
cs1 <- corExp(3, form = ~ Time | Rat)
cs1 <- initialize(cs1, BodyWeight)
Variogram(cs1)[1:10,]