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?sample --- On Wed, 7/30/08, Alessandro <alessandro.montaghi at unifi.it> wrote:> From: Alessandro <alessandro.montaghi at unifi.it> > Subject: [R] Random subset > To: r-help at r-project.org > Received: Wednesday, July 30, 2008, 2:18 PM > 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. > > > > Thanks for help > > > > alessandro > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.__________________________________________________________________ [[elided Yahoo spam]]
Hi, check ?sample n <- 200 mydata.set <- rnorm(100000) my.random.subset <- sample(x=mydata.set, size=n, replace=TRUE) my.random.subset I hope this helps, Roland 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. > > > > Thanks for help > > > > alessandro > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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. >
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 HTH, Marc Schwartz