grouping
Grouping Permutation
Description
Gives ordering of elements of a set of variables, so equivalent
values are contiguous.
Usage
grouping(...)
Arguments
| ... |
Any number of objects, all of which have the same length.
|
Details
The permutation vector is essentially that given by order(...)).
However, each character argument, arg_i, is first replaced
by match(arg_i, unique(arg_i)).
Also, note that if any argument arg_i has a class attribute, then it
is replaced by xtfrm(arg_i), just as is done in the order
function.
Value
returns the permutation vector, which is given the class "grouping." Also returns the following two
attributes, which are computed from the input vectors (perhaps
processed by
xtfrm).
- ends: the indices of the last element of each of the groups. A group
ends when at least one of the arguments, perhaps processed by xtfrm, changes value
right after this point.
- maxgrpn: the maximum group size.
See Also
Examples
grouping(c(4,5,6,4,5,5), rep(c("Old","New"),c(4,2)))
d <- data.frame(Value=c(4,5,6,4,5,5), Which=rep(c("Old","New"),c(4,2)),
stringsAsFactors=FALSE)
p <- do.call(grouping, d)
dp <- d[p,]
dp$group <- rep(seq_along(attr(p, "ends")), diff(c(0,attr(p,"ends"))))
dp