| getGroups.varFunc {nlme} | R Documentation |
This method function extracts the grouping factor associated with the
variance function represented by object, if any is present.
## S3 method for class 'varFunc': getGroups(object, form, level, data, sep)
object |
an object inheriting from class varFunc,
representing a variance function structure. |
form |
an optional formula with a conditioning expression on its
right hand side (i.e. an expression involving the |
operator). Defaults to formula(object). Not used. |
level |
a positive integer vector with the level(s) of grouping to be used when multiple nested levels of grouping are present. This argument is optional for most methods of this generic function and defaults to all levels of nesting. Not used. |
data |
a data frame in which to interpret the variables named in
form. Optional for most methods. Not used. |
sep |
character, the separator to use between group levels when
multiple levels are collapsed. The default is '/'. Not used. |
if object has a groups attribute, its value is
returned; else NULL is returned.
Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu
vf1 <- varPower(form = ~ age | Sex) vf1 <- Initialize(vf1, Orthodont) getGroups(vf1)