From: Carrie Li <carrieandstat_at_gmail.com>

Date: Thu, 03 Jun 2010 19:24:58 -0400

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. Received on Thu 03 Jun 2010 - 23:28:32 GMT

Date: Thu, 03 Jun 2010 19:24:58 -0400

On Thu, Jun 3, 2010 at 12:21 PM, Jorge Ivan Velez <jorgeivanvelez_at_gmail.com>wrote:

> Hi Carrie,

*>
**> Here are two options:
**>
**> # Option 1
**> d <- data.frame(x, t)
**> y <- with(d, ifelse(t == 0, rbinom(2, 1, 0.2), rbinom(3, 1, 0.8)))
**> y
**>
**> # Option 2 -- more general case, e.g. you do not know
**> # how many 0's and 1's you have within each strata
**> spd <- with(d, split(d, x))
**> do.call(c, lapply(spd, function(comp)
**> with(comp, ifelse(t == 0, rbinom(sum(t==0), 1, 0.2),
**> rbinom(sum(t!=0), 1, 0.8)))))
**>
**> HTH,
**> Jorge
**>
**>
**> On Thu, Jun 3, 2010 at 11:49 AM, Carrie Li <> wrote:
**>
**>> Dear R-helpers,
**>>
**>> I would like to generate a binary random variable within a stratum's
**>> stratum. Here is a simple example.
**>>
**>>
**>> ## x is the first level strata index, here I have 3 strata.
**>> x=c(rep(1,5), rep(2,5), rep(3,5))
**>>
**>> ## within x, there is a second strata indexed by t=0 and t=1
**>> t=rep(c(0,0,1,1,1),3)
**>>
**>>
**>> ## and within strata i and t=0 and t=1, I generate the random binomial
**>> variable respectively, and save in y
**>> y=rep(NA, length(x))
**>> for (i in 1:3)
**>> {
**>> y[(x==i)&(t==0)]=rbinom(2, 1, 0.2)
**>> y[(x==i)&(t==1)]=rbinom(3, 1, 0.8)
**>> }
**>>
**>>
**>> My question: is there any way to avoid the for loop, since I have the
**>> first
**>> level strata has thousands of strata. (Within each x stratum, the t only
**>> has
**>> 2 levels, 0 and 1 )
**>>
**>> Thanks for any help!
**>>
**>> Carrie
**>>
**>> [[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.
**>>
**>
**>
*

[[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. Received on Thu 03 Jun 2010 - 23:28:32 GMT

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.2.0, at Fri 04 Jun 2010 - 00:30:28 GMT.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*