logical value. Default is FALSE. If TRUE, add panel border.
margin
logical value. Default is TRUE. If FALSE, reduce plot margin.
legend
character specifying legend position. Allowed values are one of
c("top", "bottom", "left", "right", "none"). Default is "top" side position.
to remove the legend use legend = "none". Legend position can be also
specified using a numeric vector c(x, y). In this case it is possible to
position the legend inside the plotting area. x and y are the coordinates of
the legend box. Their values should be between 0 and 1. c(0,0) corresponds
to the "bottom left" and c(1,1) corresponds to the "top right" position. For
instance use legend = c(0.8, 0.2).
x.text.angle
Rotation angle of x axis tick labels. Default value is 0.
Use 90 for vertical text.
flip
logical. If TRUE, grid lines are added to y axis instead of x axis.