getGroups                package:nlme                R Documentation

_E_x_t_r_a_c_t _G_r_o_u_p_i_n_g _F_a_c_t_o_r_s _f_r_o_m _a_n _O_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n:

     This function is generic; method functions can be written to
     handle specific classes of objects. Classes which already have
     methods for this function include 'corStruct', 'data.frame',
     'gls', 'lme', 'lmList', and 'varFunc'.

_U_s_a_g_e:

     getGroups(object, form, level, data, sep)

_A_r_g_u_m_e_n_t_s:

  object: any object

    form: an optional formula with a conditioning expression on its
          right hand side (i.e. an expression involving the '|'
          operator). Defaults to 'formula(object)'.

   level: a positive integer vector with the level(s) of grouping to be
          used when multiple nested levels of grouping are present.
          This argument is optional for most methods of this generic
          function and defaults to all levels of nesting.

    data: a data frame in which to interpret the variables named in
          'form'. Optional for most methods.

     sep: character, the separator to use between group levels when
          multiple levels are collapsed.  The default is ''/''.

_V_a_l_u_e:

     will depend on the method function used; see the appropriate
     documentation.

_A_u_t_h_o_r(_s):

     Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates
     bates@stat.wisc.edu

_R_e_f_e_r_e_n_c_e_s:

     Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S
     and S-PLUS", Springer, esp. pp. 100, 461.

_S_e_e _A_l_s_o:

     'getGroupsFormula', 'getGroups.data.frame', 'getGroups.gls',
     'getGroups.lmList', 'getGroups.lme'

_E_x_a_m_p_l_e_s:

     ## see the method function documentation