R help - Mar 2010 - Matching pairs of values

I am sure someone can come up with a clever way of doing what I want---I 
don't seem to be able to.

I want to check if a pair of numbers occurs as one of the rows of an n 
by 2 matrix. If I was only checking whether a single number was in a 
vector of numbers I would use %in% but I can't see how to generalize to 
this case.

Any pointers?

David Scott


-- 
_________________________________________________________________
David Scott	Department of Statistics
		The University of Auckland, PB 92019
		Auckland 1142,    NEW ZEALAND
Phone: +64 9 923 5055, or +64 9 373 7599 ext 85055
Email:	d.scott at auckland.ac.nz,  Fax: +64 9 373 7018

Director of Consulting, Department of Statistics

David Scott-6 wrote:
> 
> I am sure someone can come up with a clever way of doing what I want---I 
> don't seem to be able to.
> 
> I want to check if a pair of numbers occurs as one of the rows of an n 
> by 2 matrix. If I was only checking whether a single number was in a 
> vector of numbers I would use %in% but I can't see how to generalize to
> this case.
> 
Would this help?

vtest <- function(x, lookfor) any(apply(x,1, function(v)
identical(v,lookfor)))
> ma <- matrix(c(2,3,1,5,7,3),ncol=2)
> ma
     [,1] [,2]
[1,]    2    5
[2,]    3    7
[3,]    1    3
> vtest(ma,c(3,7))
[1] TRUE
> vtest(ma,c(1,7))
[1] FALSE

Berend
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