getGroups.lme {nlme}R Documentation

Extract lme Object Groups


The grouping factors corresponding to the linear mixed-effects model represented by object are extracted. If more than one level is indicated in level, the corresponding grouping factors are combined into a data frame; else the selected grouping factor is returned as a vector.


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


object an object inheriting from class lme, representing a fitted linear mixed-effects model.
form this argument is included to make the method function compatible with the generic and is ignored in this method.
level an optional integer vector giving the level(s) of grouping to be extracted from object. Defaults to the highest or innermost level of grouping.
data unused
sep character, the separator to use between group levels when multiple levels are collapsed. The default is '/'.


either a data frame with columns given by the grouping factors indicated in level, or, when a single level is requested, a factor representing the selected grouping factor.


Jose Pinheiro and Douglas Bates

See Also



fm1 <- lme(pixel ~ day + day^2, Pixel,
  random = list(Dog = ~day, Side = ~1))
getGroups(fm1, level = 1:2)

[Package nlme version 3.1-80 Index]