nlme (version 3.1-31)

getGroups.data.frame: Extract Groups from a Data Frame

Description

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.

Usage

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

Value

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.

See Also

getGroupsFormula

Examples

data(Pixel)
getGroups(Pixel)
getGroups(Pixel, level = 2)