Simple Radial Tree (d3 v4; CSV; 63 Lines)

This is the simplest radial tree diagram I could create. Let me know if you think I can make it tighter.

Build notes:

It pulls data from a csv file. It uses d3.stratify() to reform links into a hierarchy. (NOTE: I ran into a challenge with d.size when moving from json to csv. While size is a feature of my data, I had to now access it from d.data.size.)
To differentiate between local variables and framework objects, I prefix variables with lowercase 'v'.

Radial Tree notes: The size method in d3.cluster().size([2 * Math.PI, Math.min(vWidth, vHeight)/2 - 10]); is both important and odd.

radius setting Math.min(vWidth, vHeight)/2 - 10]);: We choose smaller of height and width, then we divide in half to find (and set) the diagram's radius. We pull out a bit extra to ensure we have margin (so that the circles don't get clipped). I chose to subtract 10 since my cirle radius is 10 (which really translates to 10 / 2 * 2 since I'm only in danger of cutting off 1/2 my circle, but it could happen on both sides).
The first element of size sets the bredth of the diagram. While https://github.com/d3/d3-hierarchy#cluster_size mentions 360, my diagrams ended up wonky if I didn't raise this number to something much larger (maybe due to my low number of end nodes?).

From https://bl.ocks.org/denjn5/4cc1a43f41efdc0ae6b7a1bf6a7d5e4e

<!DOCTYPE html>
<meta charset='utf-8'>
<head>
    <title>Simple Radial Tree (d3 v4; CSV; 63 Lines)</title>
    <script src="https://d3js.org/d3.v4.min.js"></script>
</head>

path {
        fill: none;
        stroke: #05668D;
        opacity: 0.6;
        stroke-width: 2px;
    }
</style>

// Prepare our physical space
    var g = d3.select('svg').attr('width', vWidth).attr('height', vHeight)
        .select('g').attr('transform', 'translate(' + vWidth/2 + ',' + vHeight/2 + ')');

// Get the data from our CSV file
    d3.csv('data.csv', function(error, vCsvData) {
        if (error) throw error;

vData = d3.stratify()(vCsvData);
        drawViz(vData);
    });

function drawViz(vData) {
        // Declare d3 layout
        var vLayout = d3.cluster().size([2 * Math.PI, Math.min(vWidth, vHeight)/2 - 10]); // margin!

// Layout + Data
        var vRoot = d3.hierarchy(vData);
        var vNodes = vRoot.descendants();
        var vLinks = vLayout(vRoot).links();

// Draw on screen
        g.selectAll('path').data(vLinks).enter().append('path')
            .attr('d', d3.linkRadial()
                .angle(function (d) { return d.x; })
                .radius(function (d) { return d.y; }));

g.selectAll('circle').data(vNodes).enter().append('circle')
            .attr('r', 10)
            .attr("transform", function (d) { return "translate(" + d3.pointRadial(d.x, d.y) + ")"; });
    }
</script>

https://d3js.org/d3.v4.min.js