eSlivinski/d3.hexbin.min.js

## d3.hexbin.min.js
!function(){d3.hexbin=function(){function u(n){var r={};return n.forEach(function(n,t){var a=s.call(u,n,t)/o,e=Math.round(a),c=h.call(u,n,t)/i-(1&e?.5:0),f=Math.round(c),l=a-e;if(3*Math.abs(l)>1){var v=c-f,g=f+(f>c?-1:1)/2,m=e+(e>a?-1:1),M=c-g,d=a-m;v*v+l*l>M*M+d*d&&(f=g+(1&e?1:-1)/2,e=m)}var j=f+"-"+e,p=r[j];p?p.push(n):(p=r[j]=[n],p.i=f,p.j=e,p.x=(f+(1&e?.5:0))*i,p.y=e*o)}),d3.values(r)}function a(r){var t=0,u=0;return n.map(function(n){var a=Math.sin(n)*r,e=-Math.cos(n)*r,i=a-t,o=e-u;return t=a,u=e,[i,o]})}var e,i,o,c=1,f=1,h=r,s=t;return u.x=function(n){return arguments.length?(h=n,u):h},u.y=function(n){return arguments.length?(s=n,u):s},u.hexagon=function(n){return arguments.length<1&&(n=e),"m"+a(n).join("l")+"z"},u.centers=function(){for(var n=[],r=0,t=!1,u=0;f+e>r;r+=o,t=!t,++u)for(var a=t?i/2:0,h=0;c+i/2>a;a+=i,++h){var s=[a,r];s.i=h,s.j=u,n.push(s)}return n},u.mesh=function(){var n=a(e).slice(0,4).join("l");return u.centers().map(function(r){return"M"+r+"m"+n}).join("")},u.size=function(n){return arguments.length?(c=+n[0],f=+n[1],u):[c,f]},u.radius=function(n){return arguments.length?(e=+n,i=2*e*Math.sin(Math.PI/3),o=1.5*e,u):e},u.radius(1)};var n=d3.range(0,2*Math.PI,Math.PI/3),r=function(n){return n[0]},t=function(n){return n[1]}}();

## index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <script src="http://d3js.org/d3.v4.js"></script>
    <script src="https://d3js.org/d3-queue.v3.min.js"></script>
    <script src="./d3.hexbin.min.js"></script>
    <style>
      .states path {
        fill: #ddd;
        stroke: #fff;
        stroke-width: 2px;
      }
      .hex-mesh path{
        stroke: black;
        stroke-opacity: 0.4;
        stroke-width: 1;
        fill-opacity: 0;
      }
      .hexagons path{
        stroke-width: 2;
        stroke: white;
      }
    </style>
  </head>

  <body>

  <script>
  var width = 960,
      height = 500;

  var svg = d3.select('body')
    .append('svg')
    .attr('width', width)
    .attr('height', height);

  var projection = d3.geoAlbersUsa();

  var path = d3.geoPath()
    .projection(projection);

  var color = d3.scaleLinear()
    .range(['#fff ', '#e31a1c'])
    .domain([0, 20])
    .interpolate(d3.interpolateLab);

  var hexbin = d3.hexbin()
      .size([width, height])
      .radius(20);

  var states = svg.append('g')
    .attr('class', 'states');

  var hexagon = svg.append('g')
    .attr('class', 'hexagons');

  var mesh = svg.append('g')
    .attr('class', 'hex-mesh')
    .append('path')
      .attr('d', hexbin.mesh());

  function render (geometry, shootings) {
    states.selectAll('path')
    .data(geometry.features)
    .enter().append('path')
    .attr('d', path);

    hexagon.selectAll('path')
      .data(hexbin(shootings.map(d => { return d.properties.projected; })))
    .enter().append('path')
      .attr('transform', d => { return 'translate(' + d.x + ',' + d.y + ')'; })
      .attr('fill-opacity', 0)
      .attr('d', hexbin.hexagon(1))
      .transition()
        .attr('fill', d => { return color(d.length); })
        .attr('fill-opacity', 1)
      .transition()
        .attr('d', hexbin.hexagon(hexbin.radius()));
  }

  d3.queue()
    .defer(d3.json, 'us.geojson')
    .defer(d3.json, 'police-shootings-2015-2017.geojson')  // https://www.washingtonpost.com/graphics/national/police-shootings-2015
    .awaitAll((err, results) => {
      if (err) { return console.error(err); }

      shootings = results[1].features
        .map(d => {
          d.properties.projected = projection(d.geometry.coordinates);
          return d;
        })
        .filter(d => { return d.properties.projected; });

      render(results[0], shootings);
    });

  </script>
  </body>
</html>

## police-shootings-2015-2017.geojson

      
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    Raw
  

              police-shootings-2015-2017.geojson
            
          
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## preview.png

      
    Raw
  

              preview.png
            
          
## thumbnail.png

      
    Raw
  

              thumbnail.png
            
          
## us.geojson

      
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Display the rendered blob

    
    Raw
  

              us.geojson
            
          
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	<!DOCTYPE html>
	<html lang="en">
	<head>
	<!-- Required meta tags -->
	<meta charset="utf-8">
	<script src="http://d3js.org/d3.v4.js"></script>
	<script src="https://d3js.org/d3-queue.v3.min.js"></script>
	<script src="./d3.hexbin.min.js"></script>
	<style>
	.states path {
	fill: #ddd;
	stroke: #fff;
	stroke-width: 2px;
	}
	.hex-mesh path{
	stroke: black;
	stroke-opacity: 0.4;
	stroke-width: 1;
	fill-opacity: 0;
	}
	.hexagons path{
	stroke-width: 2;
	stroke: white;
	}
	</style>
	</head>

	<body>

	<script>
	var width = 960,
	height = 500;

	var svg = d3.select('body')
	.append('svg')
	.attr('width', width)
	.attr('height', height);

	var projection = d3.geoAlbersUsa();

	var path = d3.geoPath()
	.projection(projection);

	var color = d3.scaleLinear()
	.range(['#fff ', '#e31a1c'])
	.domain([0, 20])
	.interpolate(d3.interpolateLab);

	var hexbin = d3.hexbin()
	.size([width, height])
	.radius(20);

	var states = svg.append('g')
	.attr('class', 'states');

	var hexagon = svg.append('g')
	.attr('class', 'hexagons');

	var mesh = svg.append('g')
	.attr('class', 'hex-mesh')
	.append('path')
	.attr('d', hexbin.mesh());

	function render (geometry, shootings) {
	states.selectAll('path')
	.data(geometry.features)
	.enter().append('path')
	.attr('d', path);

	hexagon.selectAll('path')
	.data(hexbin(shootings.map(d => { return d.properties.projected; })))
	.enter().append('path')
	.attr('transform', d => { return 'translate(' + d.x + ',' + d.y + ')'; })
	.attr('fill-opacity', 0)
	.attr('d', hexbin.hexagon(1))
	.transition()
	.attr('fill', d => { return color(d.length); })
	.attr('fill-opacity', 1)
	.transition()
	.attr('d', hexbin.hexagon(hexbin.radius()));
	}

	d3.queue()
	.defer(d3.json, 'us.geojson')
	.defer(d3.json, 'police-shootings-2015-2017.geojson') // https://www.washingtonpost.com/graphics/national/police-shootings-2015
	.awaitAll((err, results) => {
	if (err) { return console.error(err); }

	shootings = results[1].features
	.map(d => {
	d.properties.projected = projection(d.geometry.coordinates);
	return d;
	})
	.filter(d => { return d.properties.projected; });

	render(results[0], shootings);
	});

	</script>
	</body>
	</html>