on 07/30/2008 01:28 PM Marc Schwartz wrote:
on 07/30/2008 01:18 PM Alessandro wrote:
Hi all,
I wish to do a random subset (i.e. 200 or 300 points) from a dataset,
but I
don't find the right code in R.
See ?sample.
Randomly select 10 elements from a 30 element vector:
Vec <- 1:30
> sample(Vec, 10)
[1] 16 5 10 29 27 30 21 1 12 28
Randomly select 5 rows from a 10 row matrix:
MAT <- matrix(1:20, 10, 2)
> MAT
[,1] [,2]
[1,] 1 11
[2,] 2 12
[3,] 3 13
[4,] 4 14
[5,] 5 15
[6,] 6 16
[7,] 7 17
[8,] 8 18
[9,] 9 19
[10,] 10 20
> MAT[sample(5), ]
[,1] [,2]
[1,] 5 15
[2,] 3 13
[3,] 4 14
[4,] 1 11
[5,] 2 12
Sorry, correction, that should be:
> MAT[sample(10, 5), ]
[,1] [,2]
[1,] 8 18
[2,] 10 20
[3,] 1 11
[4,] 6 16
[5,] 3 13
Fingers too fast there...
Marc
______________________________________________
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.
