Extract varFunc Groups

Usage

getGroups(object)

Arguments

object an object inheriting from class code{varFunc}, representing a variance function structure.

Description

This method function extracts the grouping factor associated with the variance function represented by object, if any is present.

Value

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

Author(s)

Jose Pinheiro and Douglas Bates

Examples

library(lme)
data(Orthodont)
vf1 <- varPower(form = ~ age | Sex)
vf1 <- initialize(vf1, Orthodont)
getGroups(vf1)

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