How it works...

In order to build a stacked plot, we need to supply three arguments to the aes() function. The x variable is the x-axis, y is the bar height, and fill is the color. The geom_var variable specifies the type of bar that will be used. The stat=identity value tells ggplot that we don't want to apply any transformation, and leave the data as it is. We will use the reshape package for transforming the data into the format that we need.

The result has one bar for each company, with two colors. The red color corresponds to the Adjusted Sales and the green color corresponds to the Unadjusted Sales.