[Rd] is.integer and rank

[Peter Dalgaard BSA]

Torsten Hothorn <Torsten.Hothorn@rzmail.uni-erlangen.de> writes:

> Hello, 
> 
> why does
> 
> > test <- rank(sample(10))
> > test
>  [1]  4  8  9 10  2  1  7  6  3  5
> > is.integer(test)
> [1] FALSE
> > is.double(test)
> [1] TRUE
> 
> make sense in R-1.1.1?  

Ranks have to be able to include non-integers, hence storage mode
double

> rank(c(1,2,2,3))
[1] 1.0 2.5 2.5 4.0

More confusing is:

> is.integer(1)
[1] FALSE

> is.integer(1:1)
[1] TRUE

(both of which is for a reason, although I have temporarily forgotten
why we make integer sequences integer.... Speed issues, possibly)

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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