Sankey with circular links and self-linking nodes

Update to d3-sankey-circular to allow self-linking nodes, as well as fixes to how nodes are compared to determine if they are horizontally aligned.

Also, includes minor tweaks to the layout functions to accommodate self linking links, and circular links that travel below the chart.

<!DOCTYPE html>
<html>

<head>

<title>Sankey with circular links</title>
  <style>
    body {
      font-family: 'Roboto', sans-serif;
    }

rect {
      shape-rendering: crispEdges;
    }

text {
      font-size: 12px;
      font-family: monospace;
    }

.link {
      fill: none;
    }
  </style>
</head>

<body>

<h1>Sankey with circular links</h1>

let data = data5;

const nodePadding = 40;

const circularLinkGap = 2;

var sankey = d3.sankey()
      .nodeWidth(10)
      .nodePadding(nodePadding)
      .nodePaddingRatio(0.5)
      .scale(0.5)
      .size([width, height])
      .nodeId(function (d) {
        return d.name;
      })
      .nodeAlign(d3.sankeyRight)
      .iterations(32);

var svg = d3.select("#chart").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom);

var g = svg.append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")")

var linkG = g.append("g")
      .attr("class", "links")
      .attr("fill", "none")
      .attr("stroke-opacity", 0.2)
      .selectAll("path");

var nodeG = g.append("g")
      .attr("class", "nodes")
      .attr("font-family", "sans-serif")
      .attr("font-size", 10)
      .selectAll("g");

//run the Sankey + circular over the data
    let sankeyData = sankey(data);
    let sankeyNodes = sankeyData.nodes;
    let sankeyLinks = sankeyData.links;

let depthExtent = d3.extent(sankeyNodes, function (d) { return d.depth; });

var nodeColour = d3.scaleSequential(d3.interpolateCool)
    .domain([0,width]);

//Adjust link Y coordinates based on target/source Y positions

var node = nodeG.data(sankeyNodes)
      .enter()
      .append("g");

node.append("rect")
      .attr("x", function (d) { return d.x0; })
      .attr("y", function (d) { return d.y0; })
      .attr("height", function (d) { return d.y1 - d.y0; })
      .attr("width", function (d) { return d.x1 - d.x0; })
      .style("fill", function (d) { return nodeColour(d.x0); })
      //.style("fill", "black")
      .style("opacity", 0.5)
      //.style("stroke", "black")
      .on("mouseover", function (d) {

let thisName = d.name;

node.selectAll("rect")
          .style("opacity", function (d) {
            return highlightNodes(d, thisName)
          })

d3.selectAll(".sankey-link")
          .style("opacity", function (l) {
            return l.source.name == thisName || l.target.name == thisName ? 1 : 0.3;
          })

node.selectAll("text")
          .style("opacity", function (d) {
            return highlightNodes(d, thisName)
          })
      })
      .on("mouseout", function (d) {
        d3.selectAll("rect").style("opacity", 0.5);
        d3.selectAll(".sankey-link").style("opacity", 0.7);
        d3.selectAll("text").style("opacity", 1);
      })

node.append("text")
      .attr("x", function (d) { return (d.x0 + d.x1) / 2; })
      .attr("y", function (d) { return d.y0 - 12; })
      .attr("dy", "0.35em")
      .attr("text-anchor", "middle")
      .text(function (d) { return d.name; });

node.append("title")
      .text(function (d) { return d.name + "\n" + (d.value); });

var arrowsG = linkG.data(sankeyLinks)
      .enter()
      .append("g")
      .attr("class", "g-arrow")
      .call(appendArrows, 20, 300, 4)

function highlightNodes(node, name) {

let opacity = 0.3

if (node.name == name) {
        opacity = 1;
      }
      node.sourceLinks.forEach(function (link) {
        if (link.target.name == name) {
          opacity = 1;
        };
      })
      node.targetLinks.forEach(function (link) {
        if (link.source.name == name) {
          opacity = 1;
        };
      })

return opacity;

}

</script>
</body>

</html>

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

https://d3js.org/d3-scale-chromatic.v1.min.js