# [R] value matching %in% for a number pair

William Dunlap wdunlap at tibco.com
Sun Nov 13 03:19:47 CET 2016

```> S <- list(c(1,2), c(4,3), c(3,3), c(2,3), c(4,5))
> list(c(1,2), c(3,4), c(2,3)) %in% S # is in S?
[1]  TRUE FALSE  TRUE
> match(list(c(1,2), c(3,4), c(2,3)), S) # which element of S?
[1]  1 NA  4

Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Sat, Nov 12, 2016 at 5:36 PM, John <miaojpm at gmail.com> wrote:

> Hi,
>
>    We can match one numerical value as follows
> > 3 %in% c(4,5)
> [1] FALSE
> > 3 %in% c(4,5,3)
> [1] TRUE
>
>    To see whether value pairs are identical,
> > identical(c(3,4), c(3,5))
> [1] FALSE
> > identical(c(3,4), c(3,4))
> [1] TRUE
>
>    Is there any way to test whether “A value pair is in a set of value
> pairs”? For example, can we test whether the pair (2,3) is identical to one
> of the pairs in the set S={(1,2), (4,3), (3,3), (2,3), (4,5)}?
>    In this case, the answer is yes because the 4th element of S is (2,3).
> Is there any simple way to code it? Thanks!
>
> John
>
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>
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