Message-ID: <1356662949.35504.YahooMailNeo@web142603.mail.bf1.yahoo.com>
Date: 2012-12-28T02:49:09Z
From: arun
Subject: Finding (swapped) repetitions of numbers pairs across two columns
In-Reply-To: <CAMUS-MvmNzm_bE8uAmBWhN3LbORMWT=r4jH37V9nZbaYVEeGVw@mail.gmail.com>
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.levy at gmail.com>
To: R-help Mailing List <r-help at 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
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