All Combinations of k Elements from Vector v
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)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.