[R] choosing a random sample by precentage

[Joshua Wiley]

Hi Ethan,

Sure with a bit of extra work:

x <- matrix(1:109, ncol = 1)
x[sample(nrow(x), trunc(nrow(x)*.1)), ]

you could also use round() in place of trunc(), you just need
something to get it to an integer.  If you didn't like having to type
the name several times you could make a simple function to do it for
you.

HTH,

Josh

On Thu, Jul 22, 2010 at 3:49 PM, Xebar Saram <zeltakc at gmail.com> wrote:
> hi all
>
> i have found the follwoing way to choose a random sample by sample size (200):
>
> ten_per_T2000 <- F_T2000_All[sample(nrow(F_T2000_All), 200), ]
>
>
>  but i wondered if there is a way to choose a sample size by
> precentage (10% etc..)
>
> thx
>
> ethan
>
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-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/