

_L_e_v_e_l_s _A_t_t_r_i_b_u_t_e_s

     levels(x)
     levels(x) <- value

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

     `levels' provides access to the levels attribute of a
     variable.  The first form returns the value of the lev-
     els of its argument and the second sets the attribute.

     The assignment for of `levels' is a generic function
     and new methods can be written for it.  The most impor-
     tant method is that for factors.

_S_e_e _A_l_s_o:

     `levels<-.factor', `nlevels'.

