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Last active Feb 10, 2017

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Hexagonal Binning
license: gpl-3.0

This example shows how to use the d3.hexbin plugin for hexagonal binning. 2,000 random points with a normal distribution are binned into hexagons; color encodes the number of points that fall into each bin. You can also use area encoding. Inspired by earlier work by Zachary Forest Johnson.

!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]}}();
<!DOCTYPE html>
<meta charset="utf-8">
<style>
.axis text {
font: 10px sans-serif;
}
.axis path,
.axis line {
fill: none;
stroke: #000;
shape-rendering: crispEdges;
}
.hexagon {
fill: none;
stroke: #000;
stroke-width: .5px;
}
</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script src="d3.hexbin.min.js"></script>
<script>
var margin = {top: 20, right: 20, bottom: 30, left: 40},
width = 960 - margin.left - margin.right,
height = 500 - margin.top - margin.bottom;
var randomX = d3.random.normal(width / 2, 80),
randomY = d3.random.normal(height / 2, 80),
points = d3.range(2000).map(function() { return [randomX(), randomY()]; });
var color = d3.scale.linear()
.domain([0, 20])
.range(["white", "steelblue"])
.interpolate(d3.interpolateLab);
const RADIUS = 20
var hexbin = d3.hexbin()
.size([width, height])
.radius(RADIUS);
var x = d3.scale.identity()
.domain([0, width]);
var y = d3.scale.linear()
.domain([0, height])
.range([height, 0]);
var xAxis = d3.svg.axis()
.scale(x)
.orient("bottom")
.tickSize(6, -height);
var yAxis = d3.svg.axis()
.scale(y)
.orient("left")
.tickSize(6, -width);
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
svg.append("clipPath")
.attr("id", "clip")
.append("rect")
.attr("class", "mesh")
.attr("width", width)
.attr("height", height);
svg.append("g")
.attr("clip-path", "url(#clip)")
.selectAll(".hexagon")
.data(hexbin(points))
.enter().append("path")
.attr("class", "hexagon")
.attr("d", hexbin.hexagon())
.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; })
.style("fill", function(d) { return color(d.length); })
.on('click', function(d) {
console.log(d.x, d.y)
console.log(JSON.stringify({right: [d.x + (RADIUS*2), d.y]}))
})
svg.append("g")
.attr("class", "y axis")
.call(yAxis);
svg.append("g")
.attr("class", "x axis")
.attr("transform", "translate(0," + height + ")")
.call(xAxis);
</script>
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