R: Extract corStruct Groups

getGroups.corStruct {nlme}

R Documentation

Extract corStruct Groups

Description

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

Usage

## S3 method for class 'corStruct'
getGroups(object, form, level, data, sep)

Arguments

`object`	an object inheriting from class `corStruct` representing a correlation structure.
`form`	this argument is included to make the method function compatible with the generic. It will be assigned the value of `formula(object)` and should not be modified.
`level`	this argument is included to make the method function compatible with the generic and is not used.
`data`	an optional data frame in which to evaluate the variables defined in `form`, in case `object` is not initialized and the grouping factor needs to be evaluated.
`sep`	character, the separator to use between group levels when multiple levels are collapsed. The default is `'/'`.

Value

if a grouping factor is present in the correlation structure represented by object, the function returns the corresponding factor vector; else the function returns NULL.

Author(s)

Jose Pinheiro and Douglas Bates bates@stat.wisc.edu

Examples

cs1 <- corAR1(form = ~ 1 | Subject)
getGroups(cs1, data = Orthodont)

[Package nlme version 3.1-104 Index]