[R] Subsampling out of site*abundance matrix

[David Winsemius]

set.seed "sets" the (pseudo-)random number generator in a predictable  
state so that you get the same table as I do when running the code,  
assuming you don't do any other calls to the RNG in the interim.

123 is kind of traditional as a seed for demonstration purposes, but  
in real analyses you could choose any seed favorite number.

-- 
David.
On Feb 7, 2011, at 9:51 AM, B77S wrote:

>
> Also, I really appreciate you explaining why you used factor.  I'm  
> still not
> quite sure what set.seed does (i read ?set.seed) or why you chose  
> 123... but
> it and the function below work, so that is all that matters.  :)
>
> randSub <- function(L1, s.size)
> {
> set.seed(123) 	
> samptbl <- apply(L1, 1, function(x) sample(colnames(L1), s.size,  
> prob=x,
> replace=TRUE) )
> sampdf <- as.data.frame(samptbl)
> sampdf1 <-vector("list")
> for(i in 1:nrow(L1))
> {		
> sampdf1[[i]] <-  factor(sampdf[[i]], levels= colnames(L1))
> }
> out <- t(sapply(sampdf1, table))
> }
> -- 
> View this message in context: http://r.789695.n4.nabble.com/Subsampling-out-of-site-abundance-matrix-tp3263148p3264251.html
> Sent from the R help mailing list archive at Nabble.com.
>
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David Winsemius, MD
West Hartford, CT