| getGroups.corStruct {nlme} | R Documentation |
This method function extracts the grouping factor associated with
object, if any is present.
## S3 method for class 'corStruct': getGroups(object, form, level, data, sep)
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 '/'. |
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.
Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu
cs1 <- corAR1(form = ~ 1 | Subject) getGroups(cs1, data = Orthodont)