[R] match rows of R

[arun]

Hi,
Try:
 roweqv<- function(m,v) which(!is.na(match(interaction(as.data.frame(m),drop=TRUE),paste(v,collapse="."))))
v<- c(2,5,8)
roweqv(m,v)
#[1] 2


set.seed(24)
m1<-matrix(sample(1:15,3e5,replace=TRUE),ncol=3)
v1<- c(10,12,4)

 system.time(res<- roweqv(m1,v1))
  # user  system elapsed 
  #0.132   0.000   0.130 
res
# [1]     5   381  2760  3793  9667 16881 18866 21219 24961 36220 38366 54382
#[13] 54951 55825 57167 67636 70713 71087 73284 82797 83255 85748 86216 86690
#[25] 93120 95399 96370

head(m1[res,])
#     [,1] [,2] [,3]
#[1,]   10   12    4
#[2,]   10   12    4
#[3,]   10   12    4
#[4,]   10   12    4
#[5,]   10   12    4
#[6,]   10   12    4

v2<- c(20,5,4)
roweqv(m1,v2)
#integer(0)

A.K.
----- Original Message -----
From: Sachinthaka Abeywardana <sachin.abeywardana at gmail.com>
To: "r-help at r-project.org" <r-help at r-project.org>
Cc: 
Sent: Wednesday, June 26, 2013 4:03 AM
Subject: [R] match rows of R

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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