R help - Jul 2011 - sample function with different proportions

Hi there,

I guess this is an easy one, but still: 

I would like to randomly sample 0s and 1s but in a way that I end up having for
example 70% of 1s and the rest of 0s and not 50:50 as this function
does: sample(c(0,1), 100, replace = TRUE)

Any recommendations?


Many thanks!

Ana
	[[alternative HTML version deleted]]

Hi Ana,

Look at the documentation for ?sample, specifically, the "prob"
argument.  In your case this should work:

sample(c(0,1), 100, replace = TRUE, prob = c(.3, .7))

note that you may not have *exactly* 70% 1 and 30%, in any given sample.

HTH,

Josh

On Tue, Jul 5, 2011 at 11:21 AM, Ana Kolar <annakolar at yahoo.com>
wrote:
> Hi there,
>
> I guess this is an easy one, but still:
>
> I would like to randomly sample 0s and 1s but in a way that I end up having
for example 70% of 1s and the rest of 0s and not 50:50 as this function
does:?sample(c(0,1), 100, replace = TRUE)
>
> Any recommendations?
>
>
> Many thanks!
>
> Ana
> ? ? ? ?[[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.
>
>


-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
https://joshuawiley.com/

On 05/07/2011 2:25 PM, Joshua Wiley wrote:
> Hi Ana,
>
> Look at the documentation for ?sample, specifically, the "prob"
> argument.  In your case this should work:
>
> sample(c(0,1), 100, replace = TRUE, prob = c(.3, .7))
>
> note that you may not have *exactly* 70% 1 and 30%, in any given sample.
And if you want exact counts, you can use sample to permute a vector.  
For example:

sample(rep(0:1, c(30, 70)))

Duncan Murdoch
> HTH,
>
> Josh
>
> On Tue, Jul 5, 2011 at 11:21 AM, Ana Kolar<annakolar at yahoo.com> 
wrote:
> >  Hi there,
> >
> >  I guess this is an easy one, but still:
> >
> >  I would like to randomly sample 0s and 1s but in a way that I end up
having for example 70% of 1s and the rest of 0s and not 50:50 as this function
does: sample(c(0,1), 100, replace = TRUE)
> >
> >  Any recommendations?
> >
> >
> >  Many thanks!
> >
> >  Ana
> >          [[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.
> >
> >
>
>
>