here is a possible solution:
subsets <- function (n, r, s = 1:n) {
# from V&Rs (2000) S Programming, Springer, p.49
if (mode(n) != "numeric" || length(n) != 1 || n < 1 || (n%%1) !=
0) stop("bad value of n")
if (mode(r) != "numeric" || length(r) != 1 || r < 1 || (r%%1) !=
0) stop("bad value of r")
if (!is.atomic(s) || length(s) < n) stop("s is either non-atomic
or too short")
fun <- function(n, r, s)
if (r <= 0) vector(mode(s), 0)
else if (r >= n) s[1:n]
else rbind(cbind(s[1], Recall(n - 1, r - 1, s[-1])),
Recall(n - 1, r, s[-1]))
fun(n, r, s)
}
##############
x <- c(1, 3, 5, 7, 9)
ind <- subsets(length(x), 2)
apply(matrix(x[ind], nc = ncol(ind)), 1, function(x)
as.numeric(paste(x, collapse = "")))
ind <- subsets(length(x), 3)
apply(matrix(x[ind], nc = ncol(ind)), 1, function(x)
as.numeric(paste(x, collapse = "")))
I hope it helps.
Best,
Dimitris
----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm
----- Original Message -----
From: "Clark Allan" <[EMAIL PROTECTED]>
To: <r-help@stat.math.ethz.ch>
Sent: Friday, May 27, 2005 3:24 PM
Subject: [R] r: LEXICOGRAPHIC ORDERING
HI all
i have a seemingly simple question.
given a sequence of numbers say, 1,2,3,4,5.
i would like to get all of the possible two number arrangments
(combinations), all 3 number arrangents ... 5 number arrangements
(combinations).
i.e.
in the 2 number case:
12,13,14,15,23,24,25,34,35,45
any ideas?
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