[R] a little probleme

[Thomas Lumley]

On Wed, 4 Jul 2001, Olivier Martin wrote:

> Hi all,
>
> i would like to find the best way to resolve the following problem.
> Suppoose i have a vector x of length N with k different elements.
> length(x)=N
> u<-unique(x)
> length(u)=k
>
> I would like to get a matrix M with k rows and N columns such that:
> in each line i (i=1,...,k), which(x%in%u[i]) is equal to 1 and 0 else.

Another solution

outer(unique(x),x,"==")+0

(the +0 just converts it to numeric rather than TRUE/FALSE)

	-thomas

Thomas Lumley			Asst. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

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