[R] ties in runif() output

Douglas Grove dgrove at fhcrc.org
Sat Jun 26 00:15:16 CEST 2004

I get ties in output from runif() when I generate as few as 10^5
variates and get quite a lot when I generate 10^6.  Is this 
expected??  I haven't seen any duplication with rnorm(10^6), but
see varying amounts of duplication using rexp(), rbeta() and
rgamma().  I would have thought that there'd be enough precision
that one wouldn't get ties until generating samples larger than this..

> set.seed(222)
> sum(duplicated(runif(10^5)))
[1] 4

> sum(duplicated(runif(10^6)))
[1] 140

platform i686-pc-linux-gnu
arch     i686
os       linux-gnu
system   i686, linux-gnu
status   Patched
major    1
minor    9.0
year     2004
month    04
day      13
language R

Doug Grove

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