[R] questions on data management

[Jacques VESLOT]

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"))

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Jacques VESLOT

CNRS UMR 8090
I.B.L (2ème étage)
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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
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zhijie zhang a écrit :
> 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!
> 
> 
> 
>