Re: [R] How to generate the random numbers uniformly distributed on the unit disc?

From: Peter Dalgaard <p.dalgaard_at_biostat.ku.dk>
Date: Mon 09 Oct 2006 - 10:10:33 GMT

"S.Q. WEN" <randsnews@gmail.com> writes:

> Hi,
> I want to get random number which is uniformly distributed on the unit
> disc.
> How can I do that with R?

Most easily, although perhaps not most efficiently, by using spherical coordinates:

 N <- 10000
 r <- sqrt(runif(N))
 theta <- runif(N,0,2*pi)

 x <- r*cos(theta)
 y <- r*sin(theta)
 plot(x,y,pch=".")




-- 
   O__  ---- Peter Dalgaard             Ă˜ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)                  FAX: (+45) 35327907

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