UPDATE: Here’s the final piece. Due to a few requests for it, I will soon be releasing my code. (Caveat: it’s ugly.)

Here is the next step forward in my Sankey diagram generator. While it is still far from a finished product, it actually looks like it’s supposed to, which is quite rewarding! Quite simply, I take the point in the middle of each trunk’s Y axis, map all of those values to a larger scale (to create the fanning out effect) and draw a bezier curve from the original point to the end point.

The curves are looking weird in a few spots, for instance with the largest values at the top, it appears to be more of a bulge than a curve. This may just be a matter of giving the curve more room to breathe on the X axis. Eventually I will need to come up with a nicer way to display the monetary values as well.

My next task is to gather more detailed data (specific Federal grants, for example), and draw those on to the graph as well. This should prove more of a challenge, but most of that code is already written.