R devel - Mar 2006 - Internal codes of the factor

Hello!

I am writing some functions and I repeatedly acces internal factor
codes. I figured out that internal codes are 1:n where 1 represents 1st
level, 2 2nd level etc. This is not documented and I wonder if this is
on purpose and subject to change or would be a good idea to add this to
documentation for factor? I can prepair a pacth if this is accepted.

-- 
Lep pozdrav / With regards,
    Gregor Gorjanc

----------------------------------------------------------------------
University of Ljubljana     PhD student
Biotechnical Faculty
Zootechnical Department     URI: http://www.bfro.uni-lj.si/MR/ggorjan
Groblje 3                   mail: gregor.gorjanc <at> bfro.uni-lj.si

SI-1230 Domzale             tel: +386 (0)1 72 17 861
Slovenia, Europe            fax: +386 (0)1 72 17 888

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"One must learn by doing the thing; for though you think you know it,
 you have no certainty until you try." Sophocles ~ 450 B.C.

G'day Gregor,
>>>>> "GG" == Gregor Gorjanc <gregor.gorjanc at
bfro.uni-lj.si> writes:
    GG> I am writing some functions and I repeatedly acces internal
    GG> factor codes. I figured out that internal codes are 1:n where
    GG> 1 represents 1st level, 2 2nd level etc. This is not
    GG> documented [...]
The help page for factor states in the 'Details' section:

     The encoding of the vector happens as follows. First all the
     values in 'exclude' are removed from 'levels'. If
'x[i]' equals
     'levels[j]', then the 'i'-th element of the result is
'j'.  If no
     match is found for 'x[i]' in 'levels', then the
'i'-th element of
     the result is set to 'NA'.

Note in particular the part on "then the 'i'-th element of the
result
is 'j'".  This pretty much documents that the internal codes are
1:n
and 'NA', as documented in the following sentence.



Cheers,

        Berwin

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