On Feb 17, 2011, at 1:33 PM, andrija djurovic wrote:
This is, maybe, not the best solution but I hope it will help you:
x<-data.frame(id=c(1,1,1,2,2,2,2,3,3,3,4,4), v1=c(1:12), V2=c(12:23))
do.call("rbind",by(x,x$id,function(x) x[c(sample(nrow(x),2)),]))
Andrija
Another way (and note that by is just a wrppare for tapply):
> tapply(1:nrow(x), x$id, sample, 2)
$`1`
[1] 2 3
$`2`
[1] 5 4
$`3`
[1] 10 8
$`4`
[1] 11 12
> x[unlist( tapply(1:nrow(x), x$id, sample, 2) ), ]
id v1 V2
2 1 2 13
3 1 3 14
5 2 5 16
6 2 6 17
9 3 9 20
8 3 8 19
12 4 12 23
11 4 11 22
On Thu, Feb 17, 2011 at 6:39 PM, yf <chang...@umn.edu> wrote:
But i need for each id have two data.
Like...
x
id v1 V2
1 1 1 12
2 1 2 13
4 2 4 15
5 2 5 16
8 3 8 19
9 3 9 20
11 4 11 22
12 4 12 23
So should write sample( if sample id >2 ,2). I don't know how to
write
(if
sample id >2). Thanks.
--
View this message in context:
http://r.789695.n4.nabble.com/sampling-tp3310184p3311253.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
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.
[[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.
David Winsemius, MD
West Hartford, CT
______________________________________________
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.
