Runs the ggplot_build function on the input and converts
the output data objects into a nested list with the unique values of
each of the aesthetic columns.
Usage
layersList(obj)
Value
list of aesthetics and their values for each layer in a plot
p=ggplot2::ggplot(iris,ggplot2::aes(x=Sepal.Length,y=Sepal.Width))
p=p+ggplot2::geom_point(ggplot2::aes(colour=Species))+ggplot2::geom_line()
p
p.list=layersList(p)
p.list