lowess                 package:base                 R Documentation

_S_c_a_t_t_e_r _P_l_o_t _S_m_o_o_t_h_i_n_g

_D_e_s_c_r_i_p_t_i_o_n:

     This function performs the computations for the LOWESS smoother
     (see the reference below). `lowess' returns a list containing
     components `x' and `y' which give the coordinates of the smooth.
     The smooth should be added to a plot of the original points with
     the function `lines'.

_U_s_a_g_e:

     lowess(x, y, f=2/3, iter=3, delta=.01*diff(range(x)))

_A_r_g_u_m_e_n_t_s:

    x, y: vectors giving the coordinates of the points in the scatter
          plot. Alternatively a single plotting structure can be
          specified.

       f: the smoother span. This gives the proportion of points in the
          plot which influence the smooth at each value. Larger values
          give more smoothness.

    iter: the number of robustifying iterations which should be
          performed. Using smaller values of `iter' will make `lowess'
          run faster.

   delta: values of `x' which lie within `delta' of each other replaced
          by a single value in the output from `lowess'.

_R_e_f_e_r_e_n_c_e_s:

     Cleveland, W. S. (1979) Robust locally weighted regression and
     smoothing scatterplots. J. Amer. Statist. Assoc. 74, 829-836.

     Cleveland, W. S. (1981) LOWESS: A program for smoothing
     scatterplots by robust locally weighted regression. The American
     Statistician, 35, 54.

_S_e_e _A_l_s_o:

     `loess' (in package `modreg'), a newer formula based version of
     `lowess' (with different defaults!).

_E_x_a_m_p_l_e_s:

     data(cars)
     plot(cars, main = "lowess(cars)")
     lines(lowess(cars), col = 2)
     lines(lowess(cars, f=.2), col = 3)
     legend(5, 120, c(paste("f = ", c("2/3", ".2"))), lty = 1, col = 2:3)

