[R] Finding Equal Elements in Vectors
Marc Schwartz
MSchwartz at MedAnalytics.com
Sun Feb 27 16:24:54 CET 2005
On Sun, 2005-02-27 at 16:07 +0100, Sven C. Koehler wrote:
> Hello!
>
> I have two vectors and want to know how many of their elements are
> equal -
> what's the best way to do this in R?
>
> Best regards,
>
> Sven
> a <- 1:10
> b <- 8:20
> a
[1] 1 2 3 4 5 6 7 8 9 10
> b
[1] 8 9 10 11 12 13 14 15 16 17 18 19 20
If you just want to know how many elements in 'a' are in 'b':
> sum(a %in% b)
[1] 3
If you want to know which elements in 'a' are in 'b':
> which(a %in% b)
[1] 8 9 10
See ?"%in%" and ?which for more information.
HTH,
Marc Schwartz
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