[R] Counting elements in columns

[Dennis Murphy]

length(intersect(a, b))


On Sat, Apr 16, 2011 at 8:04 PM, Jim Silverton <jim.silverton at gmail.com> wrote:
> I have two columns and I want to count hwo many pairs I have of the same
> element. For example. If I have
> a = c(1,2,3,4,5)
> b= c(12, 1, 34, 2, 5, 0, 10, 100, 11)
> It should return 3 (since 1, 2 and 5 occur in both columns).
> Columns need not be of the same length.
>
> --
> Thanks,
> Jim.
>
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