

   codes {base}                                 R Documentation

   FFaaccttoorr CCooddeess

   DDeessccrriippttiioonn::

        This (generic) function returns a numeric coding of a
        factor. It can also be used to assign to a factor using
        the coded form.

   UUssaaggee::

        codes(x)
        codes(x) <- value

   VVaalluuee::

        For an ordered factor, it returns the internal coding
        (1 for the lowest group, 2 for the second lowest,
        etc.).

        For an unordered factor, an alphabetical ordering of
        the levels is assumed, i.e the level that is coded 1 is
        the one whose name is sorted first according to the
        prevailing collating sequence. Warning: the sort order
        may well depend on the locale, and should not be
        assumed to be ASCII.

   NNoottee::

        Normally `codes' is not the appropriate function to use
        with an unordered factor. Use `unclass' or `as.numeric'
        to extract the codes used in the internal representa-
        tion of the factor, as these do not assume that the
        codes are sorted.

   SSeeee AAllssoo::

        `factor', `levels', `nlevels'.

   EExxaammpplleess::

        codes(rep(factor(c(20,10)),3))

        x <- gl(3,5)
        codes(x)[3] <- 2
        x

        data(esoph)
        ( ag <- esoph$alcgp[12:1] )
        codes(ag)

        codes(factor(1:10)) # BEWARE!

