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; area encodes the number of points that fall into each bin. You can also use color 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: steelblue; | |
| stroke: #fff; | |
| stroke-width: .5px; | |
| } | |
| </style> | |
| <body> | |
| <script src="//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 radius = d3.scale.sqrt() | |
| .domain([0, 50]) | |
| .range([0, 20]); | |
| var hexbin = d3.hexbin() | |
| .size([width, height]) | |
| .radius(20); | |
| 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", function(d) { return hexbin.hexagon(radius(d.length)); }) | |
| .attr("transform", function(d) { return "translate(" + d.x + "," + 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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