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@mbostock mbostock/.block
Last active Feb 26, 2019

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Hexagonal Binning (Color)
license: gpl-3.0
redirect: https://observablehq.com/@d3/d3-hexbin

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 Johnson.

<!DOCTYPE html>
<style>
.hexagon {
stroke: #000;
stroke-width: 0.5px;
}
</style>
<svg width="960" height="500"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="https://d3js.org/d3-hexbin.v0.2.min.js"></script>
<script>
var svg = d3.select("svg"),
margin = {top: 20, right: 20, bottom: 30, left: 40},
width = +svg.attr("width") - margin.left - margin.right,
height = +svg.attr("height") - margin.top - margin.bottom,
g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
var randomX = d3.randomNormal(width / 2, 80),
randomY = d3.randomNormal(height / 2, 80),
points = d3.range(2000).map(function() { return [randomX(), randomY()]; });
var color = d3.scaleSequential(d3.interpolateLab("white", "steelblue"))
.domain([0, 20]);
var hexbin = d3.hexbin()
.radius(20)
.extent([[0, 0], [width, height]]);
var x = d3.scaleLinear()
.domain([0, width])
.range([0, width]);
var y = d3.scaleLinear()
.domain([0, height])
.range([height, 0]);
g.append("clipPath")
.attr("id", "clip")
.append("rect")
.attr("width", width)
.attr("height", height);
g.append("g")
.attr("class", "hexagon")
.attr("clip-path", "url(#clip)")
.selectAll("path")
.data(hexbin(points))
.enter().append("path")
.attr("d", hexbin.hexagon())
.attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; })
.attr("fill", function(d) { return color(d.length); });
g.append("g")
.attr("class", "axis axis--y")
.call(d3.axisLeft(y).tickSizeOuter(-width));
g.append("g")
.attr("class", "axis axis--x")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(x).tickSizeOuter(-height));
</script>
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