A straight-forward visualization of association rules is to use a scatter plot with two interest
measures on the axes. Such a presentation can be found already in an early paper by Bayardo,
Jr. and Agrawal (1999) when they discuss sc-optimal rules.
The default method for plot() for association rules in arulesViz is a scatter plot using support
and condence on the axes. In addition a third measure (default: lift) is used as the color
(gray level) of the points. A color key is provided to the right of the plot.