A groupedData object is at least a data.frame and a
display formula that provides a grouping structure. At present we
are using an old-style class for this.
Arguments
Objects from the Class
A virtual Class: No objects may be
created from it.
Extends
Class "data.frame", directly.
Class "oldClass", by class "data.frame".
Methods
No methods defined with class "groupedData" in the signature.