Axis                package:graphics                R Documentation

Generic function to add an Axis to a Plot

Description:

     Generic function to add a suitable axis to the current plot.

Usage:

     Axis(x = NULL, at = NULL, ..., side, labels = NULL)

Arguments:

       x: an object which indicates the range over which an axis should
          be drawn

      at: the points at which tick-marks are to be drawn.

    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.

  labels: this can either be a logical value specifying whether
          (numerical) annotations are to be made at the tickmarks, or a
          character or expression vector of labels to be placed at the
          tickpoints. If this is specified as a character or expression
          vector, 'at' should be supplied and they should be the same
          length.

     ...: Arguments to be passed to methods and perhaps then to 'axis'.

Details:

     This is a generic function.  It works in a slightly non-standard
     way: if 'x' is supplied and non-NULL it dispatches on 'x',
     otherwise if 'at' is supplied and non-NULL it dispatches on 'at',
     and the default action is to call 'axis', omitting argument 'x'.

     The idea is that for plots for which either or both of the axes
     are numerical but with a special interpretation, the standard
     plotting functions (including 'boxplot', 'contour', 'coplot',
     'filled.contour', 'pairs', 'plot.default', 'rug' and 'stripchart')
     will set up user coordinates and 'Axis' will be called to label
     them appropriately.

     There are '"Date"', '"POSIXct"' and '"POSIXlt"' methods which can
     pass an argument 'format' onto the appropriate 'axis' method (see
     'axis.POSIXct').

Value:

     The numeric locations on the axis scale at which tick marks were
     drawn when the plot was first drawn (see 'Details').

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

See Also:

     'axis'.

