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

[Jeff Newmiller]

This really depends on the way you represent these pairs. Here is some food for thought:

p <- matrix( c( 1,2, 4,3, 3,3, 2,3, 4,5 ), byrow=TRUE, ncol=2 )
( 2 %in% p[,1] ) & ( 3 %in% p[,2] ) # (2,3)
( c( 2, 1, 5 ) %in% p[,1] ) & ( c( 3, 2, 5 ) %in% p[,2] ) # (2,3) (1,2) (5,5)

-- 
Sent from my phone. Please excuse my brevity.

On November 12, 2016 5:36:37 PM PST, 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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