tolEllipsePlot          package:robustbase          R Documentation

_T_o_l_e_r_a_n_c_e _E_l_l_i_p_s_e _P_l_o_t

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

     Plots the 0.975 tolerance ellipse of the bivariate data set 'x'.
     The ellipse is defined by those data points whose distance is
     equal to the squareroot of the 0.975 chisquare quantile with 2
     degrees of freedom.

_U_s_a_g_e:

     tolEllipsePlot(x, m.cov = covMcd(x), cutoff = NULL, id.n = NULL,
                    classic = FALSE, tol = 1e-07,
                    xlab = "", ylab = "",
                    main = "Tolerance ellipse (97.5%)",
                    txt.leg = c("robust", "classical"),
                    col.leg = c("red", "blue"),
                    lty.leg = c("solid","dashed"))

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

       x: a two dimensional matrix or data frame. 

   m.cov: an object similar to those of class '"mcd"'; however only its
          components 'center' and 'cov' will be used.  If missing, the
          MCD will be computed (via 'covMcd()').

  cutoff: numeric distance needed to flag data points outside the
          ellipse.

    id.n: number of observations to be identified by a label.  If not
          supplied, the number of observations with distance larger
          than 'cutoff' is used.

 classic: whether to plot the classical distances as well, 'FALSE' by
          default.

     tol: tolerance to be used for computing the inverse, see 'solve'. 
          Defaults to '1e-7'.

xlab, ylab, main: passed to 'plot.default'.

txt.leg, col.leg, lty.leg: character vectors of length 2 for the
          legend, only used if 'classic = TRUE'.

_A_u_t_h_o_r(_s):

     Peter Filzmoser, Valentin Todorov and Martin Maechler

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

     'covPlot' which calls 'tolEllipsePlot()' when desired.
     'ellipsoidhull' and 'predict.ellipsoid' from package 'cluster'.

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

     data(hbk)
     hbk.x <- data.matrix(hbk[, 1:3])
     mcd <- covMcd(hbk.x)       # compute mcd in advance
     ## must be a 2-dimensional data set: take the first two columns :
     tolEllipsePlot(hbk.x[,1:2])

     ## an "impressive" example:
     data(telef)
     tolEllipsePlot(telef, classic=TRUE)

