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.abeyward...@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
>
> [[alternative HTML version deleted]]
>
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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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