Hi, You could also use: apply(cbind(v1,v2),1,function(x) x[order(x)]) #or unique(t(apply(cbind(v1,v2),1,sort.int,method="quick")))
By comparing different methods: set.seed(51) v1<-sample(0:9,1e5,replace=TRUE) set.seed(49) v2<-sample(0:9,1e5,replace=TRUE) system.time(res1<-unique(t(apply(cbind(v1, v2), 1, sort)))) # user system elapsed # 11.373 0.188 11.918 system.time(res2<-unique(t(apply(cbind(v1,v2),1,sort.int,method="quick")))) # user system elapsed # 7.088 0.120 7.446 identical(res1,res2) #[1] TRUE system.time(res3 <- unique(t(apply(cbind(v1,v2),1,function(x) x[order(x)])))) #found to be faster # user system elapsed # 2.693 0.072 2.857 identical(res1,res3) #[1] TRUE A.K. ----- Original Message ----- From: Emmanuel Levy <emmanuel.l...@gmail.com> To: R-help Mailing List <r-help@r-project.org> Cc: Sent: Thursday, December 27, 2012 3:30 PM Subject: [R] Finding (swapped) repetitions of numbers pairs across two columns Hi, I've had this problem for a while and tackled it is a quite dirty way so I'm wondering is a better solution exists: If we have two vectors: v1 = c(0,1,2,3,4) v2 = c(5,3,2,1,0) How to remove one instance of the "3,1" / "1,3" double? At the moment I'm using the following solution, which is quite horrible: v1 = c(0,1,2,3,4) v2 = c(5,3,2,1,0) ft <- cbind(v1, v2) direction = apply( ft, 1, function(x) return(x[1]>x[2])) ft.tmp = ft ft[which(direction),1] = ft.tmp[which(direction),2] ft[which(direction),2] = ft.tmp[which(direction),1] uniques = apply( ft, 1, function(x) paste(x, collapse="%") ) uniques = unique(uniques) ft.unique = matrix(unlist(strsplit(uniques,"%")), ncol=2, byrow=TRUE) Any better solution would be very welcome! All the best, Emmanuel ______________________________________________ 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.
