[R] Programing and writing function help

[Jim Lemon]

Stephen Cole wrote:
> ...
> I have a vector of 20 values
>
> x <- c(20,18, 45, 16, 47, 47, 15, 26, 14,14,12,16,35,27,18,94,16,26,26,30)
>
> 1.
> I  want to select random pairs from this data set but do it without
> replacement exhaustively
>   
matrix(x[sample(1:20,20)],nrow=2)

then step through the columns of the resulting matrix
> I know i can select random pairs without replacement using
>
> sample(N,n,replace=F)
> However i am wondering if there is any way to get 10 random pairs from this
> data set without repeating any of the data points
> that is to say if i got a (20, 94) for one pair, i would like to get 9 other
> pairs from the data without again getting 20 or 94?
>
> 2.
> The second thing i would like to do is be able to select all possible pairs
> of numbers and calculate each pairs variance.
I think you want to use the combn function, but you are going to get a 
lot of pairs...

Jim