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Configurable hexbins

Experimenting with an in-browser hexbinner.

To dos: add k-means classification option, allow drag-and-drop data uploads, projection selection, more color scales

<!DOCTYPE html>
<meta charset="utf-8">
<link href="https://fonts.googleapis.com/css?family=Open+Sans" rel="stylesheet" type="text/css">
<style>

body,button {
  font: 12px "Open Sans", sans-serif;
}

* {
  box-sizing: border-box;
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
}

a {
  text-decoration: none;
}

h2 {
  margin: 0 0 0.25em 0;
  font-size: 1.5em;
}

h2:first-of-type {
  margin-top: 0;
}

.controls {
  position: absolute;
  top: 1em;
  left: 1em;
  padding: 1em;
  border: 1px solid #444;
}

.controls > div {
  margin-bottom: 1em;
}

.controls > div:last-of-type {
  margin-bottom: 0;
}

canvas {
  position: absolute;
  left: 0;
  top: 0;
}

.handle {
  fill: #fff;
  stroke: #000;
  stroke-opacity: .5;
  stroke-width: 1.25px;
  cursor: crosshair;
}

.axis {
  pointer-events: none;
}

.axis .domain {
  fill: none;
  stroke: #000;
  stroke-opacity: .3;
  stroke-width: 10px;
  stroke-linecap: round;
}

.axis .halo {
  fill: none;
  stroke: #ddd;
  stroke-width: 8px;
  stroke-linecap: round;
}

.button {
  background-color: #fff;
  border: 1px solid #ccc;
  color: #333;
  padding: 0.5em 1em;
  line-height: 140%;
  vertical-align: middle;
  cursor: pointer;
  text-align: center;
  display: inline-block;
}

.button:hover,
.button:focus,
.button:active,
.button.active {
  background-color: #ebebeb;
  border-color: #adadad;
}

.button:active,
.button.active {
  color: #000;
  outline: 0;
  -webkit-box-shadow: inset 0 3px 5px rgba(0, 0, 0, 0.125);
  box-shadow: inset 0 3px 5px rgba(0, 0, 0, 0.125);
}

.scale .button {
  width: 50%;
}

.num-classes .button {
  width: 20%;
}

.colors .button {
  width: 25%;
}

.colors .button > div {
  height: 1em;
  width: 100%;
}

.colors .button > div div {
  width: 20%;
  display: inline-block;
  height: 100%;
}

</style>
<body>
<canvas></canvas>
<div class="controls">
  <div class="size">
    <h2>Hexagon Size</h2>
  </div>
  <div class="scale">
    <h2>Classification</h2>
    <div>
      <button class="button active">Quantiles</button><button class="button">Equal Intervals</button>
    </div>
  </div>
  <div class="num-classes">
    <h2>Number of Classes</h2>
    <div>
      <button class="button">3</button><button class="button">4</button><button class="button active">5</button><button class="button">6</button><button class="button">7</button>
    </div>
  </div>
  <div class="colors">
    <h2>Colors</h2>
    <div>
      <div class="button active"></div><div class="button"></div><div class="button"></div><div class="button"></div>
    </div>
  </div>
  <div class="save">
    <a href="#" class="button" download="hexmap.png">Save Image</a>
  </div>
</div>
<script src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.10/d3.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/queue-async/1.0.7/queue.min.js"></script>
<script src="hexbin.js"></script>
<script src="colorbrewer.min.js"></script>
<script>

// More NYC-appropriate aspect ratio for bl.ocks.org
d3.select(self.frameElement).style("height", "960px");

var canvas = d3.select("canvas"),
    context = d3.select("canvas").node().getContext("2d");

// NY state plane
var projection = d3.geo.conicConformal()
    .parallels([40 + 2 / 3, 41 + 1 / 30])
    .rotate([74, 40 + 1 / 6]);

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

var color = d3.scale.quantile()
    .range(colorbrewer.PuRd[5]);

// Scale for hexagon radius
var radius = d3.scale.linear()
    .range([2,30]);

var points,
    bg,
    clip;

var hexbinner = d3.hexbin().radius(5);

// Get data
queue()
    .defer(d3.json,"nyc.geojson")
    .defer(d3.csv,"service-requests-311.csv") // 41k random 311 service request locations
    .await(ready);

function ready(err,nyc,data) {

// Convert to lng/lat pairs
  points = data.map(function(p){
    return [+p.lng,+p.lat];
  });

// Save bg geography lazily
  bg = nyc;

// Draw/add listeners for menus
  addHexSize();
  addScales();
  addNumClasses();
  addColors();
  d3.select(".save .button").on("click",saveCanvas);

// Keep canvas responsive
  window.onresize = resize;

// Set size once
  resize();

}

// Redraw everything
function rehex() {

// Wipe map
  context.clearRect(0,0,window.innerWidth,window.innerHeight);

// Rebin
  var bins = hexbinner(points.map(projection));

// Sorted list of bin counts
  var domain = bins.map(function(b){
    return b.length;
  }).sort(function(a,b){
    return a-b;
  });

// Update scale domain
  color.domain(domain);

context.fillStyle = "#fff";
  context.strokeStyle = "#999";
  context.fill(clip);

// Clip to background layer
  context.globalCompositeOperation = "source-atop";

var hex = new Path2D(hexbinner.hexagon());

bins.forEach(function(bin){

// Draw hexagon
    context.translate(bin.x,bin.y);
    context.fillStyle = color(bin.length);
    context.fill(hex);

// Reset transform
    context.setTransform(1, 0, 0, 1, 0, 0);

});

// Doing this on every redraw to avoid weird edges
  context.stroke(clip);

updateLegend();

}

function updateLegend() {

var domain = color.domain(),
      range = color.range(),
      min = domain[0],
      max = domain[domain.length - 1],
      breaks;

if (color.quantiles) {

breaks = color.quantiles();

breaks.unshift(min);

} else {

breaks = d3.range(range.length).map(function(i) {
      return min + (i * (max - min)/range.length);
    });

}

// Start at next int for counts
  breaks = breaks.map(Math.ceil);

context.globalCompositeOperation = "source-over";
  context.textAlign = "left";
  context.textBaseline = "top";
  context.strokeStyle = "#444";

// Put legend below the Rockaways
  var translate = projection([-73.95206451416014,40.53298071625918]);

// Don't stretch legend too far
  var width = projection([-73.73542785644531,40.594663726004995])[0] - translate[0];

context.translate(translate[0],translate[1]);

// Clear legend labels lazily
  context.clearRect(0, 20, 1000, 1000);

breaks.forEach(function(b,i){

var text = b;

context.fillStyle = range[i];

context.fillRect(0, 0, width / range.length, 20);

if (i === breaks.length - 1) {
      text += "+";
    }

context.strokeText(text, 0, 20);

context.translate(width / range.length,0);

});

// Leave it at the identity transform
  context.setTransform(1, 0, 0, 1, 0, 0);

}

// Get new window size, update all dimensions + projection
function resize() {

var width = window.innerWidth,
      height = window.innerHeight;

hexbinner.size([width, height]);

canvas.attr("width",width)
      .attr("height",height);

projection.scale(1)
      .translate([0,0]);

var b = path.bounds(bg),
      s = .95 / Math.max((b[1][0] - b[0][0]) / width, (b[1][1] - b[0][1]) / height),
      t = [(width - s * (b[1][0] + b[0][0])) / 2, (height - s * (b[1][1] + b[0][1])) / 2];

projection
      .scale(s)
      .translate(t);

// Only need to update this onresize
  clip = new Path2D(path(bg));

rehex();

}

// Draw slider for hexagon size
function addHexSize(){

var margin = { left: 10, right: 10, top: 8, bottom: 22},
      width = 250 - margin.left - margin.right,
      height = 36 - margin.top - margin.bottom,
      radius = hexbinner.radius();

var x = d3.scale.linear()
      .domain([2, 50])
      .range([0, width])
      .clamp(true);

var brush = d3.svg.brush()
      .x(x)
      .extent([radius,radius])
      .on("brush", brushed);

var axis = d3.svg.axis()
      .scale(x)
      .orient("bottom")
      .tickValues(x.domain())
      .tickFormat(function(d,i){
        return i ? "Larger" : "Smaller";
      })
      .tickSize(0)
      .tickPadding(12);

var svg = d3.select(".size").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("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height / 2 + ")")
      .call(axis)
      .select(".domain")
      .select(function() { return this.parentNode.appendChild(this.cloneNode(true)); })
        .attr("class", "halo");

svg.selectAll("text")
      .attr("dx",function(d,i){
        return i ? "4px" : "-4px";
      })
      .style("text-anchor",function(d,i){
        return i ? "end" : "start";
      });

var slider = svg.append("g")
      .attr("class", "slider")
      .call(brush);

slider.selectAll(".extent,.resize")
      .remove();

slider.select(".background")
      .attr("height", height);

var handle = slider.append("circle")
      .attr("class","handle")
      .attr("r",8)
      .attr("cx",x(radius))
      .attr("cy",height/2);

function brushed(){

value = x.invert(d3.mouse(this)[0]);
    brush.extent([value, value]);
    handle.attr("cx", x(value));
    hexbinner.radius(value);
    rehex();

}

// Menu for scale type
function addScales() {

var buttons = d3.selectAll(".scale button")
    .data([d3.scale.quantile,d3.scale.quantize]);

buttons.on("click",function(scale){

buttons.classed("active",function(f){
      return scale === f;
    });

var range = color.range();

color = scale().range(range);

rehex();

});

}

// Menu for number of colors
function addNumClasses() {

var buttons = d3.selectAll(".num-classes button")
      .data(d3.range(3,8));

buttons.on("click",function(numClasses){

buttons.classed("active",function(f){
      return numClasses === f;
    });

var colorScheme = d3.select(".colors .active").datum();

color.range(colorbrewer[colorScheme][numClasses]);

rehex();

});

}

// Menu swatches for color schemes
function addColors() {

var buttons = d3.selectAll(".colors .button")
      .data(["PuRd","Blues","OrRd","PiYG"]);

// Draw some swatches
  buttons.append("div")
    .attr("title",Object)
    .selectAll("div")
    .data(function(d){
      return colorbrewer[d][5];
    })
    .enter()
    .append("div")
      .style("background-color",Object);

buttons.on("click",function(colorScheme){

buttons.classed("active",function(f){
      return colorScheme === f;
    });

var numClasses = color.range().length;

color.range(colorbrewer[colorScheme][numClasses]);

rehex();

});

}

// For downloadable image
function saveCanvas() {
  var url = canvas.node().toDataURL();
  d3.select(this).attr("href",url);
}

</script>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.10/d3.min.js

https://cdnjs.cloudflare.com/ajax/libs/queue-async/1.0.7/queue.min.js