Learn D3
> This may feel like cheating, but it’s okay!  Examples are not merely reusable templates but tools for learning, hinting at subjects for study. “Breaking” an example by tinkering—changing stuff and seeing what happens—helps you achieve understanding faster than passive reading.I haven't had to use d3 in anger for some time but have an idea that means I need to re-learn it; I haven't finished yet but this is a great article. Thanks all for writing and/or sharing it.