I've been going through some interesting d3.js examples as an learning exercise. One noteworthy example is Peter Cook's circular heat chart. I've modified it here to have a circular animation.
Animations are fairly easy in d3.js with the
Essentially you just specify the changes you would like to do to the d3 object, and then d3
will create a transition to smoothly alter the attributes. It evens works with colours and some strings.
For more information, take a look at this tutorial.