| Variogram.corExp {nlme} | R Documentation |
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.
## S3 method for class 'corExp': Variogram(object, distance, sig2, length.out, ...)
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. |
... |
some methods for this generic require additional arguments. None are used in this method. |
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.
Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu
Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.
stopifnot(require("stats", quietly = TRUE))
cs1 <- corExp(3, form = ~ Time | Rat)
cs1 <- Initialize(cs1, BodyWeight)
Variogram(cs1)[1:10,]