[R] Question: reproducibility of random sampling with replacement

[Rui Barradas]

Hello,

Inline.

Em 01-01-2014 22:12, Chee Chen escreveu:
> Dear All,
>
> I would like to ask for your help on "reproducibility of random sampling with replacement". For example, one re-samples the rows with replacement of a residual matrix and uses the new residual matrix thus obtained to produce a statistic ; repeat this for a certain number of times.
>
> My questions:  will the above produce ever be reproducible by setting a seed?

Yes.

  Namely,  Given the same residual matrix, Ted applies the above process 
and so does Jack, will they get the same results by setting a seed?
>
> My attempt: setting seed does not freeze the command "sample" from  getting different samples,

Yes it does, you are simply not setting the seed before the first for loop.

Rui Barradas
  as from the codes:
> ====
> x= 1:20
> S = matrix(0,5,20)
> for (i in 1:5) {
>    S[i,] = sample(x, replace=FALSE)
> }
>
> set.seed(123)
>
> T = matrix(0,5,20)
> for (i in 1:5) {
>    T[i,] = sample(x, replace=FALSE)
> }
> sum(S==T)
> ===
>
> I would appreciate any comments and/or suggestions on this.
> Regards,
> Chee
>
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