Let's now look at presentation a bit. Rings are various shades of grey, but if you want to override those, you can do so per ring. Sections obviously have colours you can choose, and every data point within has the same colour... unless you override it per data point. The chart below makes it a point to override it for one of the countries.

In addition, data points can have an opacity. The library can take an optional delta-colour value for each point, a value between 0 and 1. The opacity of the bar is drawn proportional to that value. In the example below, the opacity of each bar is inversely proportional to its GDP.

Features to watch out for:

• Data points can be given a delta-colour between [0, 1], with the default being 1 (drawn as the darkest shade). If you can map another dimension of data to delta-colour, go for it.
• Data points can be given individual colours to override the section colour assigned to them.
• All features explained so far work as expected in all combinations.

Play around with these widgets to change the layout. View source to see how to configure the JSON object to invoke the library. For a refresher, go back to the previous demo. Some closing thoughts are here. Or click on: Start, Demo 1, Demo 2, Demo 3, Demo 4, Demo 5, Demo 6.