Polar chart (area encoding) by nitaku

index.js

/* polar layout
*/


(function() {
  var RADIUS, arc_generator, color, csv, data, height, max, polar, polar_data, polar_layout, radius_scale, svg, width;

  polar = function() {
    var angle, self;

    angle = null;
    self = function(data) {
      angle = 2 * Math.PI / data.length;
      data.forEach(function(d, i) {
        return d.angle = data.length > 2 ? i * angle : (i - 0.25) * angle;
      });
      return data;
    };
    self.angle = function() {
      return angle;
    };
    return self;
  };

  /* ---
  */


  csv = 'category,value\none,323\ntwo,534\nthree,230\nfour,180\nfive,190';

  data = d3.csv.parse(csv);

  data.forEach(function(d) {
    return d.value = +d.value;
  });

  max = d3.max(data, function(d) {
    return d.value;
  });

  width = 960;

  height = 500;

  RADIUS = Math.min(width, height) / 2 - 40;

  polar_layout = polar();

  polar_data = polar_layout(data);

  console.log(polar_data);

  svg = d3.select("body").append("svg").attr("width", width).attr("height", height).append("g").attr({
    transform: "translate(" + (width / 2) + ", " + (height / 2) + ")"
  });

  color = d3.scale.ordinal().range(["#1b9e77", "#d95f02", "#7570b3", "#e7298a", "#66a61e", "#e6ab02", "#a6761d", "#666666"]);

  radius_scale = d3.scale.sqrt().domain([0, max]).range([0, RADIUS]);

  arc_generator = d3.svg.arc().innerRadius(0).outerRadius(function(d) {
    return radius_scale(d.value);
  }).startAngle(function(d) {
    return d.angle - polar_layout.angle() / 2;
  }).endAngle(function(d) {
    return d.angle + polar_layout.angle() / 2;
  });

  svg.selectAll('.arc').data(polar_data).enter().append('path').attr({
    "class": 'arc',
    d: arc_generator,
    fill: function(d, i) {
      return color(i);
    }
  });

}).call(this);

index.html

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="description" content="Polar chart (area encoding)" />
  <title>Polar chart (area encoding)</title>
  <link rel="stylesheet" href="index.css">
  <script src="//d3js.org/d3.v3.min.js"></script>
</head>
<body>
  <script src="index.js"></script>
</body>
</html>

index.coffee

### polar layout ###
polar = () ->
  # defaults
  #scale = d3.scale.linear
  angle = null
  
  self = (data) ->
    angle = 2*Math.PI/data.length
    
    data.forEach (d, i) ->
      d.angle = if data.length > 2 then i * angle else (i-0.25) * angle
      
    return data
  
  self.angle = () ->
    return angle
  
  return self
    
### --- ###

csv = '''
category,value
one,323
two,534
three,230
four,180
five,190
'''

data = d3.csv.parse csv
data.forEach (d) ->  d.value = +d.value

max = d3.max(data, (d) -> d.value)

width = 960
height = 500
RADIUS = Math.min(width, height) / 2 - 40


polar_layout = polar()
polar_data = polar_layout(data)
console.log polar_data

svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
  .append("g")
    .attr
      transform: "translate(#{width/2}, #{height/2})"

color = d3.scale.ordinal()
  .range(["#1b9e77","#d95f02","#7570b3","#e7298a","#66a61e","#e6ab02","#a6761d","#666666"])
  
radius_scale = d3.scale.sqrt()
  .domain([0, max])
  .range([0, RADIUS])
      
arc_generator = d3.svg.arc()
  .innerRadius(0)
  .outerRadius((d) -> radius_scale(d.value))
  .startAngle((d) -> d.angle - polar_layout.angle()/2)
  .endAngle((d) -> d.angle + polar_layout.angle()/2)

svg.selectAll('.arc')
    .data(polar_data)
  .enter().append('path')
    .attr
      class: 'arc'
      d: arc_generator
      fill: (d, i) -> color(i)

index.css

svg {
  background-color: white;
}
.arc {
  stroke-width: 1;
  stroke: white;
  stroke-linejoin: round;
}