getCovariate.varFunc {nlme}R Documentation

Extract varFunc Covariate

Description

This method function extracts the covariate(s) associated with the variance function represented by object, if any is present.

Usage

getCovariate(object, form, data))

Arguments

object an object inheriting from class varFunc, representing a variance function structure.
form an optional formula specifying the covariate to be evaluated in object. Defaults to formula(object).
data some methods for this generic require a data object. Not used in this method.

Value

if object has a covariate attribute, its value is returned; else NULL is returned.

Author(s)

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

See Also

covariate<-.varFunc

Examples

data(Orthodont)
vf1 <- varPower(1.1, form = ~age)
covariate(vf1) <- Orthodont[["age"]]
getCovariate(vf1)

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