[Rd] Ordering of values returned by unique

[Witold Eryk Wolski]

Hi,
Is the ordering of the values returned something on what I can rely on, 
a form of a standard,  that a function called unique in R (in futher 
versions) will return the uniq elements in order of they first occurcence.

> x<-c(2,2,1,2)
> unique(x)
[1] 2 1
Its seems not to be the standard. E.g. matlab
>> x=[2,2,1,2]
x =
    2     2     1     2
>> unique(x)
ans =
    1     2
I just noted it because, the way how it is working now is extremely 
usefull for some applications (e.g tree traversal), so i use it in a 
script. But I am a little woried if I can rely on this behaviour in 
further versions. And furthermore can I assume that someone reading the 
code will think that it works in that way?
Or is it better to define a additional function?
keeporderunique<-function(x)
{
   res<-rep(NA,length(unique(x))
   count<-0
   for(i in x)
   {
       if(!i%in%res)
           {
                   count<-count+1
                    res[count]<-i
           }  
   }
   res
}

/E

--
Dipl. bio-chem. Witold Eryk Wolski         
MPI-Moleculare Genetic
Ihnestrasse 63-73 14195 Berlin           _
tel: 0049-30-83875219                   'v'
http://www.molgen.mpg.de/~wolski       /   \
mail: [EMAIL PROTECTED]  ---W-W----
     [EMAIL PROTECTED]

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