[R] binary representation of an integer?
Thomas Lumley
thomas at biostat.washington.edu
Tue Feb 15 20:42:58 CET 2000
On Tue, 15 Feb 2000, Mai Zhou wrote:
> Is there a function or other ways in R that can find the
> binary representation of an integer?
> (or list all those representations for integers 0:63, for example)
> OR do I have to built such a table?
>
> i.e. something like binary(3)= 11
> binary(4)= 100 etc.
>
Here's a function that works for integers up to 2^10-1, so that the value
can be returned as an integer (if you have a 64bit machine you may be able
to use a larger value of 10)
binary<-function(i) {
a<-2^(0:9)
b<-2*a
sapply(i,function(x) sum(10^(0:9)[(x %% b)>=a]))
}
And this one works up to 2^32-1 but returns a string with leading zeros
binarys<-function(i) {
a<-2^(31:0)
b<-2*a
sapply(i,function(x) paste(as.integer((x %% b)>=a),collapse=""))
}
Either could be improved, but it's probably not worth much effort.
-thomas
Thomas Lumley
Assistant Professor, Biostatistics
University of Washington, Seattle
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