

_A_d_d _A_r_r_o_w_s _t_o _a _P_l_o_t

     arrows(x0, y0, x1, y1, length = 0.25, angle = 30, code = 2,
            col = par("fg"), lty = NULL, xpd = FALSE)
     segments(x0, y0, x1, y1,
            col = par("fg"), lty = par("lty"), xpd = FALSE)

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

   x0,y0: coordinates of points from which to draw.

   x1,y1: coordinates of points to which to draw.

  length: length of the edges of the arrow head (in inches).

   angle: angle from the shaft of the arrow to the edge of
          the arrow head.

    code: integer code, determining kind of arrows to be
          drawn.

col, lty, xpd: usual graphical parameters as in `par'.

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

     `segments' draws a line segment and `arrows' draws an
     arrow between the point `(x0[i], y0[i])' and the point
     `(x1[i],y1[i])'.  If `code=2' an arrowhead is drawn at
     `(x0[i],y0[i])' and if `code=1' an arrowhead is drawn
     at `(x1[i],y1[i])'.  If `code=3' a head is drawn at
     both ends of the arrow.

     The graphical parameters `col' and `lty' can be used to
     specify a color an line texture for the line segments
     which make up the segments or arrows (`col' may be a
     vector).

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

     `polygon' for slightly easier and less flexible line
     drawing and `lines' for the usual polygons.

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

     x <- runif(12); y <- rnorm(12)
     i <- order(x,y); x <- x[i]; y <- y[i]
     plot(x,y, main="arrows(.) and segments(.)")
     ## draw arrows from point to point :
     s <- seq(length(x)-1)# one shorter than data
     arrows(x[s], y[s], x[s+1], y[s+1], col= 1:3)
     s <- s[-length(s)]
     segments(x[s], y[s], x[s+2], y[s+2], col= 'pink')

