[R] Why is.integer() doesn't work with single values?

[Peter Dalgaard BSA]

Sven Garbade <garbade at psy.uni-muenchen.de> writes:

> Hi all,
> 
> I don't understand the behavior of is.integer():
> 
> > x <- integer()
> > is.integer(x)
> [1] TRUE
> > x <- 10
> > is.integer(x)
> [1] FALSE
> > x <- 1:10
> > is.integer(x)
> [1] TRUE
> 
> Why is.interger() returns FALSE if x has only one element? And how can
> someone check if x is an integer but contains only one value? (R 1.5.0
> on Linux i386)

This has nothing to do with is.integer or lengths. It is the ":"
operator that tries to make its result an integer vector whenever
possible. Constant are generally floating point numbers, even when
they happen to be integers.

Try is.integer(1:1) and is.integer(c(1,2,3)).

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