Moreno -
While it's possible to do what you want with 8 individual
vectors, the problem is much easier to solve if you combine
them into a list:
v = list(c(2,5,6,8),c(3,7,9,11),c(13,4,2,7),
c(3.4,6,11,21),c(1,9,45,3),c(2,76,4,2),
c(34,7,8,1),c(2,6,1,9))
combs = combn(1:length(v),4)
res = lapply(as.data.frame(combs),function(x)do.call(cbind,v[x]))
res is a list containing the 70 matrices that you want.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Mon, 21 Sep 2009, Moreno Mancosu wrote:
Moreno,
I don't understand exactly what it is you are trying to
do. Can you explain what you want your matrices to look like? Perhaps
give an example.
Bryan
Dear Bryan,
let's try with an example: i
have 8 column vectors
v1<-matrix(c(2,5,6,8))
v2<-matrix(c(3,7,9,11))
v3<-matrix(c(13,4,2,7))
v4<-matrix(c(3.4,6,11,21))
v5<-matrix(c
(1,9,45,3))
v6<-matrix(c(2,76,4,2))
v7<-matrix(c(34,7,8,1))
v8<-matrix(c
(2,6,1,9))
I would like to form a combination of theese vectors in
order to obtain a set of matrixes in the form
"k-combinations from a
set" of n elements, when the set is the number of vectors (in this case
8)
and k is the number of columns (in this case 4):
in this example,
i would like to obtain
matrix_1
[,1] [,2] [,3] [,4]
[1,] 2 3 13 3.4
[2,] 5 7 4 6.0
[3,] 6 9 2
11.0
[4,] 8 11 7 21.0
matrix_2
[,1] [,2] [,3] [,4]
[1,] 2 3 13 1
[2,] 5 7 4 9
[3,] 6 9 2
45
[4,] 8 11 7 3
matrix_3
[,1] [,2] [,3] [,4]
[1,]
2 3 13 2
[2,] 5 7 4 76
[3,] 6 9 2 4
[4,] 8 11 7 2
[...]
matrix_n!/k!(n-k!)
[,1] [,2] [,
3] [,4]
[1,] 1 2 34 2
[2,] 9 76 7 6
[3,] 45
4 8 1
[4,] 3 2 1 9
I hope I was more clear!
However, thanks in advance,
Moreno
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