I suggest using vectorization :

find_row <- function(m,v) { which(!(abs(rowSums(m - rep(v, each = nrow(m)))
)) > 0) }

The function matroweqv mentioned above would give any row with the first
element equal to the first element in vector v.
The function find_row matches each row of the matrix as a whole to the
vector v.


2013/6/26 Sachinthaka Abeywardana <sachin.abeywardana@gmail.com>

> Hi all,
>
> What would be an efficient way to match rows of a matrix to a vector?
>
> ex:
>
> m<-matrix(1:9, nrow=3)
>
> m     [,1] [,2] [,3]
> [1,]    1    4    7
> [2,]    2    5    8
> [3,]    3    6    9
>
> #################################
> which(m==c(2,5,8))        # I want this to return 2
> ######################
>
> Thanks,
> Sachin
>
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>
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>



-- 
Sincerely yours,
Yulia Matveyeva,
Department of Statistical Modelling,
Faculty of Mathematics and Mechanics,
St Petersburg State University, Russia

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