set functions

[Jonathan Rougier]

On 4 Jan 2000, Peter Dalgaard BSA wrote:

> Watch:
> 
> > x<-1:50000
> > y<-x[order(runif(50000))]
> > "equiv2" <- function(x, y) all(c(match(x, y, 0)>0, match(y, x, 0)>0))
> > equiv<-function(x,y) 
> +     length(x<-unique(x))==length(y<-unique(y)) && 
> +     all(sort(x)==sort(y)) 
> > system.time(equiv2(x,y))
> [1] 3.10 0.02 3.00 0.00 0.00
> > system.time(equiv(x,y))
> [1] 0.77 0.00 1.00 0.00 0.00

Yup -- that's much quicker!  To re-ask the original question, would it be
reasonable to include such a function along with the other set functions?
Cheers, Jonathan.

Jonathan Rougier                       Science Laboratories
Department of Mathematical Sciences    South Road
University of Durham                   Durham DH1 3LE

"[B]egin upon the precept ... that the things we see are to be 
 weighed in the scale with what we know"  (Meredith, 1879, The Egoist)

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