D3 Examples - Categorical colour scale generator

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<!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>
  <script src="https://npmcdn.com/babel-core@5.8.34/browser.min.js"></script>
  <script type="text/javascript" src="https://cdn.jsdelivr.net/gh/gka/chroma.js/chroma.min.js"></script>
​
  <style>
    svg {
      width: 800px;
      height: 800px;
    }
  </style>
</head>
​
<body>
  <button onclick="generate()">Generate</button>
  <svg></svg>
  <script>
    //inspire by brian cort, you can maximise angular separation by using the golden angle 
    //https://briancort.com/colour-in-data-visualization-part-2-applications/
    function generate(){
    
    var goldenangle = Math.round(180*(3-Math.sqrt(5)))
    var goldenRatio = (1+Math.sqrt(5))/2
    var numberofcolours = 8
    var lightnessRange=[40,75]
    var lightnessStep=(lightnessRange[1]-lightnessRange[0])*(1/goldenRatio)
  
    var chromaRange=[40,60]
    var chromaStep=(chromaRange[1]-chromaRange[0])*(1/goldenRatio)
    
    var hues=[268]
    for(i=1;i<numberofcolours;i++){
      hues.push((hues[0]+i*goldenangle)%360)
    }
      
    var chromas=[]
    chromas[0]=Math.random() * (chromaRange[1] - chromaRange[0]) + chromaRange[0]
​
    for(i=0;i<numberofcolours;i++){
      if(chromas[i]+chromaStep>chromaRange[1]){chromas.push(chromas[i]+chromaStep-chromaRange[1]+chromaRange[0])}
      else{
        chromas.push(chromas[i]+chromaStep)
      }
    }
 console.log(chromas)
      
    var lightnesses=[]
    lightnesses[0]=Math.random() * (lightnessRange[1] - lightnessRange[0]) + lightnessRange[0]
    for(i=0;i<numberofcolours;i++){
      if((lightnesses[i]+lightnessStep)>lightnessRange[1]){lightnesses.push((lightnesses[i]+lightnessStep-lightnessRange[1]+lightnessRange[0]))}
      else{
        lightnesses.push(lightnesses[i]+lightnessStep)
      }
    }
    
    console.log(lightnesses)
    colors=[]
    for(i=0;i<numberofcolours;i++){
      colors.push(chroma.hcl([hues[i],chromas[i],lightnesses[i]]).hex())
    }
​
      console.log(colors)
      
      
//     var colors = chroma.cubehelix()
//                   .hue(1.1)
//                              .start(268)
//                   .rotations(numberofcolours*0.5*goldenangle)
//                   .gamma(1)
//                   .lightness([0.4,0.75])
//                 .scale() // convert to chroma.scale
//                   .correctLightness()
//                   .colors(numberofcolours);
      
      
    var svg = d3.select('svg');
    svg.selectAll("*").remove()
      
    var perRow = 4;
    var size = 150;
    var g = svg.selectAll('g')
        .data(colors).enter().append('g')
        .attr('transform', (d, i) => {
        var x = (i % perRow + 1) * size;
        var y = (Math.floor(i / perRow) + 1) * size;
        return 'translate(' + [x, y] + ')';
      }).attr('fill', d => d);
    
    g.append('circle')
        .attr('r', size / 4);
    
    g.append('text')
        .attr('y', size / 4 + 15)
        .attr('text-anchor', 'middle')
        .attr('dy', '.35em')
        .text((d, i) => d);
    }
​
  </script>
</body>
​
    