[R] counting numbers without replicates in a vector

[Peter Dalgaard]

Ray Brownrigg <ray at mcs.vuw.ac.nz> writes:

> > I am just wondering if there is an easy way to count
> > in a numeric vector how many numbers don't have
> > replicates. 
> > For example, 
> > a=c(1,1,2,2,3,4,5), how can I know there are three
> > numbers (3, 4 and 5) without replicates?
> > 
> How about:
> length(table(a)[table(a) == 1])

Also, probably inefficient, but rather neat:

> setdiff(a,a[duplicated(a)])
[1] 3 4 5


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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