Radar charts

The radar graph can be used as follows:

var Radar = require('paths/radar');
var data = [
  { hp: 45, attack: 49, defense: 49, sp_attack: 65, sp_defense: 65, speed: 45 },
  { hp: 60, attack: 62, defense: 63, sp_attack: 80, sp_defense: 80, speed: 60 },
  { hp: 80, attack: 82, defense: 83, sp_attack: 100, sp_defense: 100, speed: 80 },
  { hp: 45, attack: 25, defense: 50, sp_attack: 25, sp_defense: 25, speed: 35 }
]
var radar = Radar({
  data: data,
  accessor: {
    attack: function(x) { return x.attack; },
    defense: function(x) { return x.defense; },
    speed: function(x) { return x.speed; }
  },
  compute: {
    color: function(i) { return somePalette[i]; }
  },
  max: 100,
  center: [20, 15],
  r: 30,
  rings: 5
});

Parameters:

• data: contains an array of data to be plotted.
• accessor: an object that describes how to extract the various features from the data. The keys of this object correspond to the axes that are shown in the radar chart, and associated to each key is a function that maps a datum to its value along this axis. accessor is optional in the case where each datum is itself an object with numeric properties. For instance, if in the example above accessor was left out, we would obtain a radar graph of hexagons.
• max: represents the ideal maximum of each feature. max is optional; if it is left out, it is computed as the actual maximum of each feature, but one may want to override the computed value, for instance for constancy of scale during an animation.
• r and center: the radius and the center of the figure, respectively. So, the whole figure is scaled in such a way that a feature with value max will be sent to a distance r from the center.
• rings (optional, default 3): the number of polygonal rings that shall appear in the chart.
• compute (optional): see the introduction.

The return value from Radar is an object with the properties curves and rings. curves is an array of objects, each one having the properties polygon, item and index, where polygon contains the actual path object. rings is an array of path objects, representing concentric regular polygons of increasing radius.