abline               package:graphics               R Documentation

_A_d_d _a _S_t_r_a_i_g_h_t _L_i_n_e _t_o _a _P_l_o_t

_D_e_s_c_r_i_p_t_i_o_n:

     This function adds one or more straight lines through the current
     plot.

_U_s_a_g_e:

     abline(a, b, untf = FALSE, ...)
     abline(h=, untf = FALSE, ...)
     abline(v=, untf = FALSE, ...)
     abline(coef=, untf = FALSE, ...)
     abline(reg=, untf = FALSE, ...)

_A_r_g_u_m_e_n_t_s:

     a,b: the intercept and slope.

    untf: logical asking to _untransform_.  See Details.

       h: the y-value for a horizontal line.

       v: the x-value for a vertical line.

    coef: a vector of length two giving the intercept and slope.

     reg: an object with a 'coef' component. See Details.

     ...: graphical parameters.

_D_e_t_a_i_l_s:

     The first form specifies the line in intercept/slope form
     (alternatively 'a' can be specified on its own and is taken to
     contain the slope and intercept in vector form).

     The 'h=' and 'v=' forms draw horizontal and vertical lines at the
     specified coordinates.

     The 'coef' form specifies the line by a vector containing the
     slope and intercept.

     'reg' is a regression object which contains 'reg$coef'.  If it is
     of length 1 then the value is taken to be the slope of a line
     through the origin, otherwise, the first 2 values are taken to be
     the intercept and slope.

     If 'untf' is true, and one or both axes are log-transformed, then
     a curve is drawn corresponding to a line in original coordinates,
     otherwise a line is drawn in the transformed coordinate system.
     The 'h' and 'v' parameters always refer to original coordinates.

     The graphical parameters 'col' and 'lty' can be specified as
     arguments to 'abline'; see 'par' for details.

_R_e_f_e_r_e_n_c_e_s:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

_S_e_e _A_l_s_o:

     'lines' and 'segments' for connected and arbitrary lines given by
     their _endpoints_. 'par'.

_E_x_a_m_p_l_e_s:

     data(cars)
     z <- lm(dist ~ speed, data = cars)
     plot(cars)
     abline(z)

