[R] rbinom for a matrix

ACroske Audy3272 at yahoo.com
Wed Jul 9 21:48:01 CEST 2008


Ben:
Thanks for the reply. One further question, and this is where my novice
status at R shows through. The code makes sense, but what would I put it for
"m"? Is it the same number for all three (that was my first thought since it
was the same placeholder for all three). Number of rows in the matrix is 56.
There are 2576 total cells (observations). Each cell has its own
probability.
Thanks for your help!




Ben Bolker wrote:
> 
> ACroske <Audy3272 <at> yahoo.com> writes:
> 
>> 
>> 
>> I have a large matrix full of probabilities; I would like to convert each
>> probability to a 1 or a 0 using rbinom.
>> How can I do this on the entire matrix? The matrix was converted from a
>> raster ArcMap dataset, so the matrix is essentially a map. Because of
>> this,
>> I have no column headings.
>> Thanks! 
> 
>   How about
> 
> matrix(rbinom(length(m),prob=m,size=1),nrow=nrow(m))
> 
>   or (perhaps marginally more efficiently?)
> 
> y <- (runif(m)<m)
> storage.mode(y) <- "double"
> 
>   Ben Bolker
> 
> ______________________________________________
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> PLEASE do read the posting guide
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> and provide commented, minimal, self-contained, reproducible code.
> 
> 

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