[R] Sampling with replacement

William Dunlap wdunlap at tibco.com
Wed Jun 16 22:12:27 CEST 2010

```> -----Original Message-----
> From: r-help-bounces at r-project.org
> [mailto:r-help-bounces at r-project.org] On Behalf Of Somnath Somnath
> Sent: Wednesday, June 16, 2010 10:28 AM
> To: r-help at r-project.org
> Subject: Re: [R] Sampling with replacement
>
> Thanks for all those reply. Is there any general rule to
> determine how many
> samples I would get from a population of size "n", I draw a
> sample of size
> "m" ("m" may be greater than "n") if sample is drawn with replacement?

If you consider two samples equivalent if they
differ only in their ordering (e.g., c(1,2,2)
is equivalent to c(2,1,2) and c(2,2,1)) then
choose(n+m-1, m)
If order matters then it is
n^m

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> Thanks,
>
> 2010/6/16 Jorge Ivan Velez <jorgeivanvelez at gmail.com>
>
> > Hi Rafael,
> >
> > You might try:
> >
> > > r <- expand.grid(rep(list(1:20), 4))
> > > dim(r)
> > [1] 160000      4
> >
> > HTH,
> > Jorge
> >
> >
> > 2010/6/16 Rafael Björk <>
> >
> >> If you for some reason want to be shown all the possible
> combinations, try
> >> expand.grid(1:20,1:20,1:20,1:20) (ugly code). Don't use
> this for sampling.
> >>
> >> hth Rafael
> >>
> >> 2010/6/16 Jorge Ivan Velez <>
> >>
> >> Try
> >>>
> >>> sample(20, 4, replace = TRUE)
> >>>
> >>> HTH,
> >>> Jorge
> >>>
> >>>
> >>> On Wed, Jun 16, 2010 at 10:20 AM, Somnath Somnath <> wrote:
> >>>
> >>> > Dear all, good morning,
> >>> >
> >>> > I have a population, let say members are tagged with
> some simple number
> >>> > like
> >>> > 1,2,3,...20. I want to draw a sample with replacement
> of size 4 (say,
> >>> can
> >>> > be
> >>> > more than 20 also). Is there any R function which will
> show me all such
> >>> > possible samples?
> >>> >
> >>> > Thanks
> >>> >
> >>> >        [[alternative HTML version deleted]]
> >>> >
> >>> > ______________________________________________
> >>> > R-help at r-project.org mailing list
> >>> > https://stat.ethz.ch/mailman/listinfo/r-help
> >>> > http://www.R-project.org/posting-guide.html
> >>> > and provide commented, minimal, self-contained,
> reproducible code.
> >>> >
> >>>
> >>>        [[alternative HTML version deleted]]
> >>>
> >>> ______________________________________________
> >>> R-help at r-project.org mailing list
> >>> https://stat.ethz.ch/mailman/listinfo/r-help
> >>> http://www.R-project.org/posting-guide.html
> >>> and provide commented, minimal, self-contained, reproducible code.
> >>>
> >>
> >>
> >
>
> 	[[alternative HTML version deleted]]
>
>

```