

sortedXyData {nls}                           R Documentation

_C_r_e_a_t_e _a _s_o_r_t_e_d_X_y_D_a_t_a _o_b_j_e_c_t

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

     This is a constructor function for the class of `sort-
     edXyData' objects.  These objects are mostly used in
     the `initial' function for a self-starting nonlinear
     regression model, which will be of the `selfStart'
     class.

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

     sortedXyData(x, y, data)

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

       x: a numeric vector or an expression that will evalu-
          ate in `data' to a numeric vector

       y: a numeric vector or an expression that will evalu-
          ate in `data' to a numeric vector

    data: an optional data frame in which to evaluate
          expressions for `x' and `y', if they are given as
          expressions

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

     A `sortedXyData' object. This is a data frame with
     exactly two numeric columns, named `x' and `y'.  The
     rows are sorted so the `x' column is in increasing
     order.  Duplicate `x' values are eliminated by averag-
     ing the corresponding `y' values.

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

     Jose Pinheiro and Douglas Bates

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

     `selfStart', `NLSstClosestX', `NLSstLfAsymptote',
     `NLSstRtAsymptote'

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

     library( nls )
     data( DNase )
     DNase.2 <- DNase[ DNase$Run == "2", ]
     sortedXyData( expression(log(conc)), expression(density), DNase.2 )

