

codes {base}                                 R Documentation

_F_a_c_t_o_r _C_o_d_e_s

_D_e_s_c_r_i_p_t_i_o_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_s_a_g_e_:

     codes(x)
     codes(x) <- value

_V_a_l_u_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_o_t_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_e_e _A_l_s_o_:

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

_E_x_a_m_p_l_e_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!

