

getGroupsFormula(nlme)                       R Documentation

_E_x_t_r_a_c_t _G_r_o_u_p_i_n_g _F_o_r_m_u_l_a

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

     The conditioning expression associated with `for-
     mula(object)' (i.e. the expression after the `|' opera-
     tor) is returned either as a named list of one-sided
     formulas, or a single one-sided formula, depending on
     the value of `asList'. The components of the returned
     list are ordered from outermost to innermost level and
     are named after the grouping factor expression.

_U_s_a_g_e_:

     getGroupsFormula(object, asList)

_A_r_g_u_m_e_n_t_s_:

  object: any object from which a formula can be extracted.

  asList: an optional logical value. If `TRUE' the returned
          value with be a list of formulas; else, if `FALSE'
          the returned value will be a one-sided formula.
          Defaults to `FALSE'.

_V_a_l_u_e_:

     a one-sided formula, or a list of one-sided formulas,
     with the grouping structure associated with `for-
     mula(object)'. If no conditioning expression is present
     in `formula(object)' a `NULL' value is returned.

_A_u_t_h_o_r_(_s_)_:

     Jose Pinheiro and Douglas Bates

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

     `getGroupsFormula.gls', `getGroupsFormula.lmList',
     `getGroupsFormula.lme', `getGroupsFormula.reStruct',
     `getGroups'

_E_x_a_m_p_l_e_s_:

     library(nlme)
     getGroupsFormula(y ~ x | g1/g2)

