Military Invasions

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<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    var margin = {top: 20, right: 10, bottom: 20, left: 10};
    
    var width = 960 - margin.left - margin.right,
        height = 500 - margin.top - margin.bottom;
    
    var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
		.attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", `translate(${margin.left}, ${ margin.top})`);
    
    d3.csv("MergedIMIData1947-2005.csv", function(error, data) {
      if (error) throw error;
      
      let code_to_idx = {}
      let idx_to_code = {}
      let next_idx = 0
      
      function to_idx(code) {
        if (code in code_to_idx) {
          return code_to_idx[code]
        }
        code_to_idx[code] = next_idx
        idx_to_code[next_idx] = code
        next_idx += 1
        return next_idx -1
      }
      
      for (row of data) {
        console.log(to_idx(row['intervener']))
        console.log(to_idx(row['target']))
        console.log(to_idx(row['intervener']))
				break;
      }
    });
    
    
    
// From https://mkweb.bcgsc.ca/circos/guide/tables/
var matrix = [
  [11975,  5871, 8916, 2868],
  [ 1951, 10048, 2060, 6171],
  [ 8010, 16145, 8090, 8045],
  [ 1013,   990,  940, 6907]
];

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    outerRadius = Math.min(width, height) * 0.5 - 40,
    innerRadius = outerRadius - 30;

var formatValue = d3.formatPrefix(",.0", 1e3);

var chord = d3.chord()
    .padAngle(0.05)
    .sortSubgroups(d3.descending);

var arc = d3.arc()
    .innerRadius(innerRadius)
    .outerRadius(outerRadius);

var ribbon = d3.ribbon()
    .radius(innerRadius);

var color = d3.scaleOrdinal()
    .domain(d3.range(4))
    .range(["#000000", "#FFDD89", "#957244", "#F26223"]);

var g = svg.append("g")
    .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")")
    .datum(chord(matrix));

var group = g.append("g")
    .attr("class", "groups")
  .selectAll("g")
  .data(function(chords) { return chords.groups; })
  .enter().append("g");

group.append("path")
    .style("fill", function(d) { return color(d.index); })
    .style("stroke", function(d) { return d3.rgb(color(d.index)).darker(); })
    .attr("d", arc);

var groupTick = group.selectAll(".group-tick")
  .data(function(d) { return groupTicks(d, 1e3); })
  .enter().append("g")
    .attr("class", "group-tick")
    .attr("transform", function(d) { return "rotate(" + (d.angle * 180 / Math.PI - 90) + ") translate(" + outerRadius + ",0)"; });

groupTick.append("line")
    .attr("x2", 6);

groupTick
  .filter(function(d) { return d.value % 5e3 === 0; })
  .append("text")
    .attr("x", 8)
    .attr("dy", ".35em")
    .attr("transform", function(d) { return d.angle > Math.PI ? "rotate(180) translate(-16)" : null; })
    .style("text-anchor", function(d) { return d.angle > Math.PI ? "end" : null; })
    .text(function(d) { return formatValue(d.value); });

g.append("g")
    .attr("class", "ribbons")
  .selectAll("path")
  .data(function(chords) { return chords; })
  .enter().append("path")
    .attr("d", ribbon)
    .style("fill", function(d) { return color(d.target.index); })
    .style("stroke", function(d) { return d3.rgb(color(d.target.index)).darker(); });

// Returns an array of tick angles and values for a given group and step.
function groupTicks(d, step) {
  var k = (d.endAngle - d.startAngle) / d.value;
  return d3.range(0, d.value, step).map(function(value) {
    return {value: value, angle: value * k + d.startAngle};
  });
}

</script>
</body>

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