row indices, names or logical vector of appropriate length (i.e. typically locations, observations, etc)
j
column indices, names or logical vector of appropriate length. DO NOT USE if you are
not sure what you are doing. The result will be a conventional data.frame, probably with the
stacking structure destroyed.
...
generic parameters, ignored.
drop
logical, if selection results in one single row or column selected, return a vector?
Value
the DataFrameStack or data.frame of the selected rows and columns.