[R] Question: reproducibility of random sampling with replacement

2014-01-01 Thread Chee Chen
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? 
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, 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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Re: [R] Question: reproducibility of random sampling with replacement

2014-01-01 Thread 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

[[alternative HTML version deleted]]

__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.



__
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and provide commented, minimal, self-contained, reproducible code.


Re: [R] Question: reproducibility of random sampling with replacement

2014-01-01 Thread Rolf Turner


Why on earth would you expect S and T to be the same given
what you have done.  I am unable to rightly apprehend the
confusion of ideas that could provoke such a question,
(Charles Babbage).

You have to set the *same* seed before each construction.
I.e. do set.seed(123) before creating S; then do set.seed(123)
again before creating T.  If you do so, S and T will be
identical.

cheers,

Rolf Turner

P. S. T is not a good name for an object; too easy to confuse
with TRUE.  Not an egregious sin, but to be avoided.

R. T.

On 02/01/14 11:12, Chee Chen wrote:

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? 
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, 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.


__
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
and provide commented, minimal, self-contained, reproducible code.


Re: [R] Question: reproducibility of random sampling with replacement

2014-01-01 Thread Jeff Newmiller
If you want to reproduce the same sequence twice, then you need to set the seed 
at the beginning of each calculation. You are only doing it for the second 
calculation below.
---
Jeff NewmillerThe .   .  Go Live...
DCN:jdnew...@dcn.davis.ca.usBasics: ##.#.   ##.#.  Live Go...
  Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/BatteriesO.O#.   #.O#.  with
/Software/Embedded Controllers)   .OO#.   .OO#.  rocks...1k
--- 
Sent from my phone. Please excuse my brevity.

Chee Chen chee.c...@yahoo.com wrote:
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? 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, 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

   [[alternative HTML version deleted]]

__
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
and provide commented, minimal, self-contained, reproducible code.

__
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
and provide commented, minimal, self-contained, reproducible code.


Re: [R] Question: reproducibility of random sampling with replacement

2014-01-01 Thread Bert Gunter
You have to set the same seed before each random number generation!
You did not do this.



Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom.
H. Gilbert Welch




On Wed, Jan 1, 2014 at 2:12 PM, Chee Chen chee.c...@yahoo.com wrote:
 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? 
 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, 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

 [[alternative HTML version deleted]]

 __
 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
 and provide commented, minimal, self-contained, reproducible code.

__
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
and provide commented, minimal, self-contained, reproducible code.