combs {caTools} | R Documentation |
Finds all unordered combinations of k
elements from vector
v
.
combs(v,k)
v |
Any numeric vector |
k |
Number of elements to choose from vector |
combs(v,k)
(where v
has length n
) creates a matrix with
n!/((n-k)! k!) (n
choose k
) rows
and k
columns containing all possible combinations of n
elements
taken k
at a time.
Jarek Tuszynski (SAIC) jaroslaw.w.tuszynski@saic.com
I discovered recently that R packages already have two functions with
similar capabilities:
combinations
from gTools package and
Also similar to Matlab's nchoosek
function (http://www.mathworks.com/access/helpdesk/help/techdoc/ref/nchoosek.html)
combs(2:5, 3) # display examples combs(c("cats", "dogs", "mice"), 2) a = combs(1:4, 2) b = matrix( c(1,1,1,2,2,3,2,3,4,3,4,4), 6, 2) stopifnot(a==b)