[R] rbinom for a matrix

[Ben Bolker]

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Dylan Beaudette wrote:
| On Wednesday 09 July 2008, 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
|>
|
| Wait a second. Are you trying to convert each probability into the most
| likely '1' or '0' through rounding? The code example above will give
you a
| different answer every time you run it. Is that what you are looking for?
|
| Just curious,
|
| Dylan
|

~   I assumed that since the original poster said "convert each
probability to a 1 or 0 using rbinom" that they did indeed want
a random assignment, rather than rounding ...
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