[R] why does sample(x, n) give the same n items in every separate runs?

Dieter Menne dieter.menne at menne-biomed.de
Thu Oct 30 22:12:11 CET 2008

Shuhua Zhan <szhan <at> uoguelph.ca> writes:

> smallvec<-c(8,12,9,6,13,20,16,11,8,5)  
> largevec<-c(400,300,550,600,210,420,380,600,450,500)
> generdm<-c() ## a random set of genes
> for( i in 1:length(smallvec)){
# try to chop down this line and add a print to understand
# what is going on

> ## rownames(largedf) gives gene names ordered by levels in 
> }

Since your code does not run, and you do not show how you got your 
result, it is a bit of guesswork. I believe it has nothing to do with 
sample(), but rather with the way you "store" (=not store) the results. 
Your way of storing looks a bit like PHP.

Try a variation of this one

generdm = list()
for (i in 1:10)
  generdm[[i]] = rnorm(10) # put your sample construct here


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