[R] Pairwise combination

[David Winsemius]

On May 11, 2010, at 1:45 PM, chen jia wrote:

> Hi there,
>
> I am looking for a function that takes a vector as input and generates
> all pair wise combination of the elements of the input vector.

?combn

>
> For example, the input vector is c(1,2,3,4). The output vector is c(1
> and 2, 1 and 3, 1 and 4, 2 and 3, 2 and 4, 3 and 4).

That's not a vector.

> The
> representation here is generic.
>
> I can use a for loop to do it, but it gets slow when the number of
> elements of the input vector is large.
>
> Best,
> Jia
>


David Winsemius, MD
West Hartford, CT