xtfrm
Auxiliary Function for Sorting and Ranking
A generic auxiliary function that produces a numeric vector which
will sort in the same order as x
.
Usage
xtfrm(x)
Arguments
 x
 an R object.
Details
This is a special case of ranking, but as a less general function than
rank
is more suitable to be made generic. The default
method is similar to rank(x, ties.method = "min",
na.last = "keep")
, so NA
values are given rank NA
and all
tied values are given equal integer rank.
The factor
method extracts the codes. The
Surv
method sorts first on times and then on
status code(s), finally on timme2
if present. Note that with
the conventional status codes this sorts individuals still alive before
deaths.
The default method will unclass the object if
is.numeric(x)
is true but otherwise make use of
==
and >
methods for the class of x[i]
(for
integers i
), and the is.na
method for the class of
x
, but might be rather slow when doing so.
This is an internal generic primitive, so S3 or S4 methods can be written for it.
Value

A numeric (usually integer) vector of the same length as
x
.