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.abeyward...@gmail.com> To: "r-help@r-project.org" <r-help@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 [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
