[R] intersect more than two sets

Weiwei Shi helprhelp at gmail.com
Tue Apr 24 21:43:03 CEST 2007

I had a similar solution by using frequency but having more codes :(

I also like the "recursive" idea : I initially tried to use rapply,
however, which can only take one-arg function.

thanks, everyone.


On 4/24/07, hadley wickham <h.wickham at gmail.com> wrote:
> On 4/24/07, Tony Plate <tplate at acm.org> wrote:
> > I don't think there's that sort of "apply-reduce" function in R, but for
> > this problem, the last line below happens to be a "one-liner":
> Only if you have character data though:
> > x <- lapply(1:10, function(i) sample(20, 15))
> > names(which(table(unlist(x))==10))
> [1] "14"
> (not that it's hard to turn that back into a number)
> Hadley

Weiwei Shi, Ph.D
Research Scientist
GeneGO, Inc.

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III

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