How to force y position of one branch in d3 sankey plugin?

Question

I would like to force one branch of sankey diagram to be on top.

Instead of diagram like this:

Answer 1

Note To be honest, I never used that plugin. I don't see an option to get the desired behaviour directly - thus I looked at the source of sankey.js to make the adjustments. Below I show how I'd modify - you might want to do it more thoroughly :)

Idea

Looking at the code of sankey.js, you see that the nodes are placed (y-direction) using the center function:

function center(node) {
  return node.y + node.dy / 2;
}

As I don't see a parameter to change that behaviour, you can change it to:

function center(node) {
  return 0;
}

If you then also revert the sorting order:

function ascendingDepth(a, b) {
  return b.y - a.y;
}

you get the following picture: