R help - Jan 2003 - Weird options(digits=n) behaviour

I noticed some very weird behaviour of the function: options(digits=n),
where n is the number of digits you would expect to get in R calculations.
     Let's take a example:
> options(digits=4)
> getdata(caso.pool.k3.r3.e2)
[1]  6.053  2.641 -3.639 14.259  6.082

     Which works fine... now, trying again, with different data:
> options(digits=4)
> getdata(controle.pool.k3.r3.e2)
[1] -0.03091  1.60310 -4.90588  5.07379 -0.04418
>
    Which gives me 6 digits instead of 6. If I try digits=2, it then works
with this data:
> options(digits=2)
> getdata(controle.pool.k3.r3.e2)
[1] -0.031  1.603 -4.906  5.074 -0.044

   But not with the first one:
> getdata(caso.pool.k3.r3.e2)
[1]  6.1  2.6 -3.6 14.3  6.1


   getdata source code is as folllows:

function(v) {
 o <- c(mean(v),sd(v),min(v),max(v),median(v))
 o
}


    What is going on?

  

--

Fernando Henrique Ferraz Pereira da Rosa <mentus at gmx.de> writes:
>      I noticed some very weird behaviour of the function:
options(digits=n),
> where n is the number of digits you would expect to get in R calculations.
>      Let's take a example:
> 
> > options(digits=4)
> > getdata(caso.pool.k3.r3.e2)
> [1]  6.053  2.641 -3.639 14.259  6.082
> 
>      Which works fine... now, trying again, with different data:
> 
> > options(digits=4)
> > getdata(controle.pool.k3.r3.e2)
> [1] -0.03091  1.60310 -4.90588  5.07379 -0.04418
> >
>     Which gives me 6 digits instead of 6. If I try digits=2, it then works
> with this data:
The 'digits' option sets the minimum number of significant digits.
Some values in that array are printed to 6 significant digits but the
first and last have only 4 significant digits.

Fernando Henrique Ferraz Pereira da Rosa <mentus at gmx.de> writes:
> > options(digits=4)
> [1]  6.053  2.641 -3.639 14.259  6.082
> [1] -0.03091  1.60310 -4.90588  5.07379 -0.04418
> > options(digits=2)
> [1] -0.031  1.603 -4.906  5.074 -0.044
> [1]  6.1  2.6 -3.6 14.3  6.1
>     What is going on?
This is normal. digits=4 means that you need at least four significant
digits of the result. When you print vectors all values get printed in
the same format. Notice that in the second case -0.03091 has 4
significant digits and -0.04418 ditto and in the 3rd case likewise.
6.1 has two significant digits by the same conventions.

-- 
   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