On Wed, Aug 06, 2008 at 06:32:43PM -0400, Giuseppe Paleologo wrote:
> I was posed the following problem/teaser:
>
> given two matrices, come up with an "elegant" (=fast & short) function that
> returns a matrix with all and only the non-duplicated columns of both
> matrices; the column order does not matter. In essence, a matrix equivalent
> of union(x,y), where x and y are vectors. I could not come with anything
> nice. Any ideas?
union.matrices <- function(a, b) {
u <- cbind(a,b)
u[,!duplicated(u, MARGIN=2)]
}
?
(Obviously not attempting to deal with issues of identity of columns containing
real numbers)
Dan
>
> Giuseppe
>
> --
> Giuseppe A. Paleologo :: Email: [EMAIL PROTECTED] :: AOL: gappy3000 ::
> Skype :: gappy3000 :: Gtalk: paleologo :: Mobile: 917.331.3497
> fact: 2^32,582,657-1 is a prime
>
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