| getGroups.data.frame {nlme} | R Documentation |
Each variable named in the expression after the | operator on
the right hand side of form is evaluated in object. If
more than one variable is indicated in level they are combined
into a data frame; else the selected variable is returned as a vector.
When multiple grouping levels are defined in form and
level > 1, the levels of the returned factor are obtained by
pasting together the levels of the grouping factors of level greater
or equal to level, to ensure their uniqueness.
## S3 method for class 'data.frame': getGroups(object, form, level, data, sep)
object |
an object inheriting from class data.frame. |
form |
an optional formula with a conditioning expression on its
right hand side (i.e. an expression involving the |
operator). Defaults to formula(object). |
level |
a positive integer vector with the level(s) of grouping to be used when multiple nested levels of grouping are present. Defaults to all levels of nesting. |
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, from outer to inner, or, when a single
level is requested, a factor representing the selected grouping
factor.
Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu
getGroups(Pixel) getGroups(Pixel, level = 2)