Voronoi binning (animated)

Group data points around the largest points.

The recipe is as follows:

sort data points according to their sizes (here size = d[3])
use top 10% points as Voronoi sites
bin all data points according to their Voronoi cell, using voronoi.find(). The binning is rendered by using the Voronoi sites's color.

See also the static version — much less code to parse!

Original work by Philippe Rivière for d3-voronoi (issue 17).

<!DOCTYPE html>
<meta charset="utf-8">
<style>
</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
 
var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

d3.interval(algo, 9000);

algo();
  
  
function algo() {
  
var color = d3.scaleOrdinal().range(d3.schemeCategory20);

var n = 4000;
  
var data = d3.range(n)
    .map(function(d,i) { return [Math.random() * width, Math.random() * height, color(i), Math.random()]; });

var polygon = svg.append("g")
    .attr("class", "polygons");

var voronoi = d3.voronoi() 
    .size([width, height]);

var sites = data.sort(function(a,b) {
  return d3.descending(a[3], b[3]);
})
.slice(0,n/10);

sites.forEach(function(d) {
    d[4] = true;
})

var dots = d3.select('svg')
.append('g')
.selectAll('circle')
.data(data)
.enter()
.append('circle')
.attr('r', function(d) {return 10 * d[3] * d[3];})
.attr('transform', function(d) { return 'translate('+ [ d[0], d[1] ] +')'; })
.attr('fill', 'white')
.attr('stroke', '#444')
.attr('stroke-width', 1)
.attr('opacity', 1) 
;

var diagram = voronoi(sites);

diagram.find = function (x, y, radius){ 
  // optimization: start from most recent result  
  var i, next = diagram.find.found || Math.floor(Math.random() * diagram.cells.length);
  var cell = diagram.cells[next] || diagram.cells[next=0];
  var dx = x - cell.site[0], 
      dy = y - cell.site[1],
      dist = dx*dx + dy*dy;
  
 
  do { 
    cell = diagram.cells[i=next]; 
    next = null;
    cell.halfedges.forEach(function(e) {
      var edge = diagram.edges[e];
      var ea = edge.left;
      if (ea === cell.site || !ea) {
        ea = edge.right;
      }
      if (ea){
				var dx = x - ea[0],
            dy = y - ea[1],
            ndist = dx*dx + dy*dy;
        if (ndist < dist){
          dist = ndist;
          next = ea.index;
          return;
        }
      }
    });

} while (next !== null);

diagram.find.found = i;
  if (!radius || dist < radius * radius) return cell.site;
};

polygon.selectAll("path") 
  .data(diagram.polygons())
  .enter().append("path")
      .attr("d", function(d) { return d ? "M" + d.join("L") + "Z" : null; })
      .attr("fill", function(d,i) { return sites[i][2] })
      .attr("fill-opacity", 0.001) 
.attr('stroke', 'white')
.transition()
.delay(2000)
.duration(2000)
.attr("stroke", '#777')
.attr("fill-opacity", 0.2)

dots.transition()
.duration(2000)
.attr('fill', function(d) { return d[4] ? d[2] : 'white'; })
.attr('stroke-width', function(d) { return d[4] ? 4 : 0.5; })
;

dots
.transition()
.delay(1000)
.attr('opacity', function(d) { return d[4] ? 1 : 0.4; });

dots
.transition()
.delay(4000)
.duration(2000)
.attr('fill', function(d) {
  var found = diagram.find(d[0],d[1]);
  return sites[found.index][2];
})
.attr('opacity', 1);

polygon
.attr('opacity', 1)
.transition().delay(6000)
.duration(2000)
.attr('opacity', 0.1)
.remove();

svg.selectAll('g')
  .attr('opacity', 1)
  .transition()
  .delay(8000)
  .duration(500)
  .attr('opacity', 0)
    .remove();

}

</script>

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