Hello DC,

Great question. You would think this could be a relatively simple change, but it isn’t.

The measurements taken for the layout are really based on a horizontal spread. That being said it is not impossible to do what you want, but it will require a bit of tweaking to the src/viz/weightedtree.js file.

Here is a great link to help get you started: http://bl.ocks.org/d3noob/8326869

You will want to start by looking at three areas in src/viz/weightedtree.js

1. Initializing the d3.svg.diagonal().projection(function (d) { return [d.x,d.y] });
2. Changing related code in the measure() function for setting the appropriate width/height of the tree.nodeSize() and other related measures.
3. Changing the code in the update() function so it translates the nodes to the correct position using d.x,d.y instead of d.y,d.x. And also changing how the labels are laid out.

So while not impossible to do, there is no simply parameter you can change that will do it automatically.

– Tom