Initialize varFunc Object
Usage
initialize(object, data, ...)
Arguments
object
|
an object inheriting from class code{varFunc},
representing a variance function structure.
|
data
|
a data frame in which to evaluate the variables named in
formula(object) .
|
...
|
this argument is included to make this method compatible
with the generic.
|
Description
This method initializes object
by evaluating its associated
covariate(s) and grouping factor, if any is present, in data
;
determining if the covariate(s) need to be updated when the
values of the coefficients associated with object
change;
initializing the log-likelihood and the weights associated with
object
; and assigning initial values for the coefficients in
object
, if none were present. The covariate(s) will only be
initialized if no update is needed when coef(object)
changes.Value
an initialized object with the same class as object
representing a variance function structure.Author(s)
Jose Pinheiro and Douglas BatesSee Also
Examples
library(lme)
data(Orthodont)
vf1 <- varPower(form = ~age|Sex)
vf1 <- initialize(vf1, Orthodont)