DS Aug, Code 1

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>
  <style>
  </style>
</head>

<body>
  <canvas id='canvas'></canvas>
  <script>
		var canvas = document.getElementById('canvas');
    var ctx = canvas.getContext('2d');
    
    // data from olympics diving
    var data = [{
      "country": "China",
      "athletes": ["A. Chen", "Y. Lin"],
      "total": 496.98,
      "breakdown": [
        [2, 56.4, [9.5,9.5,9.5,9,9.5,9], [9.5,9.0,9.5,9.5,9.5]],
        [2, 52.20, [9.0,9.5,10.0,7.0,7.5,8.0], [9.0,8.5,8.0,9.0,9.0]],
        [3.4, 85.68, [7.5,7.0,8.5,8.5,8.0,8.5], [9.0,8.5,8.5,8.5,9.0]],
        [3.4, 88.74, [8.0,8.0,8.0,9.0,8.5,8.5], [8.5,9.0,9.0,9.0,9.0]],
        [3.8, 104.88, [9.0,9.0,9.0,8.5,8.5,8.5], [9.0,9.5,9.5,9.5,9.5]],
        [3.3, 89.10, [8.5,8.5,8.5,9.0,9.5,8.5], [9.0,9.5,9.0,9.0,9.5]]
      ]
    }];
    
    // properties
    var padding = 25;
    var width = canvas.width = 1200;
    var height = canvas.height = 1200;
    var colors = {'China': [[255,0,0], [255,255,0]]};
    var TWO_PI = 2 * Math.PI;
    
    var maxRadius = 50;
    var radiusScale = d3.scaleLinear().range([25, maxRadius]);
    var yScale = d3.scaleLinear().range([0, 1]);
    function processData(data) {
    	_.each(data, function(d) {
        d.processed = _.map(d.breakdown, function(score) {
          var sum = _.reduce(score[3], function(memo, num) {
            return memo + num;
          }, 0);
          return _.map(score[2], function(num) {return num * sum});
        });
      });
      
      var difficulty = _.chain(data).map('breakdown').flatten().map(0).value();
      var minRadius = _.min(difficulty);
      var maxRadius = _.max(difficulty);
      var scores = _.chain(data).map('processed').flattenDeep().value();
      var minY = _.min(scores);
      var maxY = _.max(scores);
      
      radiusScale.domain([minRadius, maxRadius]);
      yScale.domain([minY, maxY]);
    }
    
    // generate the flow line, given one event for one team
    function generateFlowData(team) {
      var gradient = ctx.createRadialGradient(0, 0, 0, 0, 0, maxRadius);
      gradient.addColorStop(1, 'rgba(' + colors[team.country][0] + ',0.2)');
      gradient.addColorStop(0, 'rgba(' + colors[team.country][1] + ',0.2)');
      
      return {
        centerX: padding,
        centerY: (height - maxRadius) / 2,
        color: gradient,
        param: 0,
        phase: (team.total / 1000) * TWO_PI, // i think phase is used for rotation
        globalPhase: (team.total / 1000) * TWO_PI, // globalPhase is for yOffset
        radii: _.map(team.breakdown, function(scores) {
          return radiusScale(scores[0]);
        }),
        points: _.map(team.processed, function(scores) {
        	return generateCircleData(scores);
      	}),
        length: _.map(team.breakdown, function(scores) {
          return Math.round(scores[1]) * 3;
        })
      }
    }
    
    // generate the data for just one of the circles in the flow line
    // majority of this function is taken from
    // Dan Gries's tutorial https://rectangleworld.com/blog/archives/462
    // in particular the function setLinePoints
    function generateCircleData(scores) {
      var circle = {
				first: {x: 0, y: 1}
      };
      var last = {x: 1, y: 1};
      var minY = maxY = 1;
      var point, nextPoint;
      var dx, newX, newY;
      
      // connect first point with the last
      circle.first.next = last;
      _.each(scores, function(score) {
        point = circle.first;
        while (point.next) {
          nextPoint = point.next;
          dx = nextPoint.x - point.x;
          newX = 0.5 * (point.x + nextPoint.x);
          newY = 0.5 * (point.y + nextPoint.y);
          // vary the y-pos by the score, but subtract it
          // by what is around the mid-point so that
          // some are positive and others are negative
          newY += dx * (yScale(score) * 2 - 1);
          
          var newPoint = {x: newX, y: newY};
          
          //min, max
          if (newY < minY) {
            minY = newY;
          }
          else if (newY > maxY) {
            maxY = newY;
          }
          
          // insert mid-point
          newPoint.next = nextPoint;
          point.next = newPoint;
          
          point = nextPoint;
        }
      })
      
//       normalize to values between 0 and 1
      if (maxY != minY) {
        var normalizeRate = 1/(maxY - minY);
        point = circle.first;
        while (point != null) {
          point.y = normalizeRate*(point.y - minY);
          point = point.next;
        }
      }
      
      return circle;
    }
    
    function drawFlowLine(flow) {
      
      // for now just draw one circle
      var theta, rad;
      var point1, point2;
      var radii, length;
      var x0, y0;
      var cosParam, yOffset;
      var drawCount = 0;
      
      for (i = 0; i < flow.points.length - 1; i += 1) {
        radii = flow.radii[i];
        length = flow.length[i];
        flow.param = 0;
        ctx.strokeStyle = flow.color;
        
        _.times(length, function() {
          drawCount += 1;
        
          // first set up styling
          ctx.beginPath();

flow.phase += 0.0002;
          flow.param += 1/length;

point1 = flow.points[i].first;
          point2 = flow.points[i + 1].first;

cosParam = 0.5 - 0.5 * Math.cos(Math.PI * flow.param);
          theta = flow.phase;
          rad = (point1.y + cosParam * (point2.y - point1.y)) * flow.radii[i];
          
          flow.centerX += 0.5;
          yOffset = 40 * Math.sin(flow.globalPhase + drawCount/600*TWO_PI);

ctx.setTransform(1, 0, 0, 1, flow.centerY + yOffset, flow.centerX);

x0 = rad * Math.cos(theta);
          y0 = rad * Math.sin(theta);
          // draw the first point
          ctx.lineTo(x0, y0);
          while (point1.next && point2.next) {
            point1 = point1.next;
            point2 = point2.next;

theta = TWO_PI * (point1.x + cosParam * (point2.x - point1.x)) + flow.phase;
            rad = (point1.y + cosParam * (point2.y - point1.y)) * flow.radii[i];

x0 = rad * Math.cos(theta);
            y0 = rad * Math.sin(theta);

ctx.lineTo(x0, y0);
  //           console.log(x0, y0)
          }

ctx.closePath();
          ctx.stroke();
        });
      }
      
    }
    
    processData(data);
    var flow = generateFlowData(data[0]);
    drawFlowLine(flow);
  </script>
</body>

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