Hi Wallace,

Have you tried playing with sample()? Note that you can apply this function
both to whole dataframes, as well as specific items within a vector. If you
play with applying the function to different ways of indexing your sample
data, you will likely arrive at your solution.

for example:

a<-data.frame(c(1:10),c(21:30))

sample(a[,2],2) #randomly draw two numbers from a column

sample(a[2,],2) #randomly draw two numbers from a row

a[sample(nrow(a),5,replace=T),] #ranomly draw four whole rows with
replacement

You may also find subet() helpful, based on your description.

HTH,

Mike

On Thu, Nov 18, 2010 at 9:43 AM, wangwallace <talenttree@gmail.com> wrote:

>
> Dear Ista Zahn-2,
>
> If you can give me some advice, I really appreciate it. I have been working
> on it for days. it seems hard for some novice of R like me to write
> flexible
> functions myself.
>
> This is for my dissertation. CSE and WSE are two scales of the same
> construct. The sampling strategy I wanted above allows me check how the
> items of these two scales vary within person and across person.
>
> Also, I added another rule: draw 1000 random samples...
>
> Again, Thanks!
>
> Wallace
> --
> View this message in context:
> http://r.789695.n4.nabble.com/New-Sampling-question-tp3047885p3048948.html
>  Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@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<http://www.r-project.org/posting-guide.html>
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Michael Rennie, Research Scientist
Fisheries and Oceans Canada, Freshwater Institute
Winnipeg, Manitoba, CANADA

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