[R] A kind of set operation in R

[Bert Gunter]

On Thu, Apr 5, 2012 at 3:07 PM, Dirk Eddelbuettel <edd at debian.org> wrote:
>
> Julio,
>
> Nobody mentioned the _set_ operations union(), intersect(), setdiff(),
> which are described under 'help(union)' (and the other names, of course)

... but which are basically wrappers for match().

-- Bert



>
>  R> X <- c(10:13, 17,18)
>  R> Y <- c(11,12,17,18)
>  R> intersect(X, Y)            # gives the actual values
>  [1] 11 12 17 18
>  R> X %in% intersect(X, Y)     # use %in% to map to bool as desired
>  [1] FALSE  TRUE  TRUE FALSE  TRUE  TRUE
>  R>
>
> Oh, and no need to reply on-list to thousands of list subscribers if you
> found this helpful.  These one-line 'thanks' message are not that universally
> useful, even though they are very polite :)
>
> Dirk
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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