The numeric locations on the axis scale at which tick marks were
drawn when the plot was first drawn.
Arguments
side
An integer specifying which side of the plot the axis is to be
drawn on. The axis is place as follows: 1 = below, 2 = left, 3 = above and
4 = right.
at
The points at which tick-marks are to be drawn.
include.symbol
Whether to include a dollar or percent symbol, where
the symbol chosen depends on the function.
simplify
For dollars, simplify the amount to use abbreviations of
"k", "m", "b", or "t" when numbers tend to be in
the thousands, millions, billions, or trillions, respectively.