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.
USAGE:
getGroups(object, form, level)
REQUIRED ARGUMENTS:
object
an object inheriting from class
lme, representing
a fitted linear mixed-effects model.
OPTIONAL ARGUMENTS:
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.
VALUE:
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.
SEE ALSO:
EXAMPLES:
fm1 <- lme(pixel ~ day + day^2, Pixel,
random = list(Dog = ~day, Side = ~1))
getGroups(fm1, level = 1:2)