[Rd] Internal codes of the factor

[Berwin A Turlach]

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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