axis                package:graphics                R Documentation

_A_d_d _a_n _A_x_i_s _t_o _a _P_l_o_t

_D_e_s_c_r_i_p_t_i_o_n:

     Adds an axis to the current plot, allowing the specification of
     the side, position, labels, and other options.

_U_s_a_g_e:

     axis(side, at = NULL, labels = TRUE, tick = TRUE, line = NA,
          pos = NA, outer = FALSE, font = NA, vfont = NULL,
          lty = "solid", lwd = 1, col = NULL, padj = NA, ...)

_A_r_g_u_m_e_n_t_s:

    side: an integer specifying which side of the plot the axis is to
          be drawn on.  The axis is placed as follows: 1=below, 2=left,
          3=above and 4=right.

      at: the points at which tick-marks are to be drawn.  Non-finite
          (infinite, 'NaN' or 'NA') values are omitted.  By default,
          when 'NULL', tickmark locations are computed, see Details
          below.

  labels: this can either be a logical value specifying whether
          (numerical) annotations are to be made at the tickmarks, or a
          vector of character strings to be placed at the tickpoints.

    tick: a logical value specifying whether tickmarks should be drawn

    line: the number of lines into the margin which the axis will be
          drawn.  This overrides the value of the graphical parameter
          'mgp[3]'.  The relative placing of tickmarks and tick labels
          is unchanged.

     pos: the coordinate at which the axis line is to be drawn: this
          overrides the values of both 'line' and 'mgp[3]'.

   outer: a logical value indicating whether the axis should be drawn
          in the outer plot margin, rather than the standard plot
          margin.

    font: font for text.

   vfont: vector font for text.

lty, lwd: line type, width for the axis line and the tick marks.

     col: color for the axis line and the tick marks.  The default
          'NULL' means to use 'par("fg")'.

    padj: adjustment for each string perpendicular to the reading
          direction. For strings parallel to the axes, 'padj=0' means
          right or top alignment,  and 'padj=1' means left or bottom
          alignment. If 'padj' is not a finite value (the default), the
          value of 'par("las")' determines the adjustment.  For strings
          plotted perpendicular to the axis the default is to centre
          the string.

     ...: other graphical parameters may also be passed as arguments to
          this function, particularly, 'cex.axis', 'col.axis' and
          'font.axis' for axis annotation, 'mgp' for positioning, 'tck'
          or 'tcl' for tick mark length and direction, 'las' for
          vertical/horizontal label orientation, or 'fg' instead of
          'col', see 'par' on these.

_D_e_t_a_i_l_s:

     The axis line is drawn from the lowest to the highest value of
     'at', but will be clipped at the plot region. Only ticks which are
     drawn from points within the plot region (up to a tolerance for
     rounding error) are plotted, but the ticks and their labels may
     well extend outside the plot region.

     When 'at = NULL', pretty tick mark locations are computed
     internally (the same way 'axTicks(side)' would) from 'par("usr",
     "lab")' and 'par("xlog")' (or '"ylog"').

     Several of the graphics parameters affect the way axes are drawn.
     The vertical (for sides 1 and 3) positions of the axis and the
     tick labels are controlled by 'mgp', the size and direction of the
     ticks is controlled by 'tck' and 'tcl' and the appearance of the
     tick labels by 'cex.axis', 'col.axis' and 'font.axis' with
     orientation controlled by 'las' (but not 'srt', unlike S which
     uses 'srt' if 'at' is supplied and 'las' if it is not).  See 'par'
     for details.

_V_a_l_u_e:

     This function is invoked for its side effect, which is to add an
     axis to an already existing plot.

_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:

     'axTicks' returns the axis tick locations corresponding to
     'at=NULL'; 'pretty' is more flexible for computing pretty tick
     coordinates and does _not_ depend on (nor adapt to) the coordinate
     system in use.  

     Several graphics parameters affecting the appearance are
     documented  in 'par'.

_E_x_a_m_p_l_e_s:

     plot(1:4, rnorm(4), axes=FALSE)
     axis(1, 1:4, LETTERS[1:4])
     axis(2)
     box() #- to make it look "as usual"

     plot(1:7, rnorm(7), main = "axis() examples",
          type = "s", xaxt = "n", frame = FALSE, col = "red")
     axis(1, 1:7, LETTERS[1:7], col.axis = "blue")
     # unusual options:
     axis(4, col = "violet", col.axis="dark violet", lwd = 2)
     axis(3, col = "gold", lty = 2, lwd = 0.5)

