Dear friends, suppose i have two datasets: A and B A: id<-1:6 x<-c(1,2,3,4,5,6) y<-c(2,4,6,8,3,2) xy<-data.frame(id,x,y) B m<-c(1,1,3,3,5,5) n<-c(2,2,6,6,3,3) mn<-data.frame(m,n) Now, i want to perfomr two tasks: 1. get a subset of B,no duplicate values,: C: m n 1 2 3 6 5 3 2.Extract the values in A on the conditions that x=m and y=n the results should be: id x y 1 1 2 3 3 6 5 5 3 Thanks very much! -- Kind Regards, Zhi Jie,Zhang ,PHD Department of Epidemiology School of Public Health Fudan University Tel:86-21-54237149 [[alternative HTML version deleted]]
merge(mn[sample(1:nrow(mn), 3, rep=F),], xy,
by.x=c("m","n"), by.y=c("x","y"))
-------------------------------------------------------------------
Jacques VESLOT
CNRS UMR 8090
I.B.L (2?me ?tage)
1 rue du Professeur Calmette
B.P. 245
59019 Lille Cedex
Tel : 33 (0)3.20.87.10.44
Fax : 33 (0)3.20.87.10.31
http://www-good.ibl.fr
-------------------------------------------------------------------
zhijie zhang a ?crit :> Dear friends,
> suppose i have two datasets: A and B
> A:
> id<-1:6
> x<-c(1,2,3,4,5,6)
> y<-c(2,4,6,8,3,2)
> xy<-data.frame(id,x,y)
> B
> m<-c(1,1,3,3,5,5)
> n<-c(2,2,6,6,3,3)
> mn<-data.frame(m,n)
> Now, i want to perfomr two tasks:
> 1. get a subset of B,no duplicate values,:
> C:
> m n
> 1 2
> 3 6
> 5 3
>
> 2.Extract the values in A on the conditions that x=m and y=n
> the results should be:
> id x y
> 1 1 2
> 3 3 6
> 5 5 3
> Thanks very much!
>
>
>
>
mnu <- unique(mn[order(mn$m,mn$n),])
mnu$p <- table(paste(mn$m, mn$n))
merge(mnu[sample(1:nrow(mnu), size=3, prob=mnu$p, replace=F),
c("m","n")], xy, by.x=c("m","n"),
by.y=c("x","y"))
-------------------------------------------------------------------
Jacques VESLOT
CNRS UMR 8090
I.B.L (2?me ?tage)
1 rue du Professeur Calmette
B.P. 245
59019 Lille Cedex
Tel : 33 (0)3.20.87.10.44
Fax : 33 (0)3.20.87.10.31
http://www-good.ibl.fr
-------------------------------------------------------------------
zhijie zhang a ?crit :> Dear friends,
> suppose i have two datasets: A and B
> A:
> id<-1:6
> x<-c(1,2,3,4,5,6)
> y<-c(2,4,6,8,3,2)
> xy<-data.frame(id,x,y)
> B
> m<-c(1,1,3,3,5,5)
> n<-c(2,2,6,6,3,3)
> mn<-data.frame(m,n)
> Now, i want to perfomr two tasks:
> 1. get a subset of B,no duplicate values,:
> C:
> m n
> 1 2
> 3 6
> 5 3
>
> 2.Extract the values in A on the conditions that x=m and y=n
> the results should be:
> id x y
> 1 1 2
> 3 3 6
> 5 5 3
> Thanks very much!
>
>
>
>