A simple visualization of an exponential model using d3.geom.quadtree and Mitchell’s Best-Candidate algorithm as its backbone. See the approximated bounded exponential model, next.
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January 8, 2016 19:28
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Exponential Model
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<!DOCTYPE html> | |
<meta charset="utf-8"> | |
<style type="text/css"> | |
body { | |
width: 1024px; | |
margin-top: 0; | |
margin: auto; | |
font-family: "Lato", "PT Serif", serif; | |
color: #222222; | |
padding: 0; | |
font-weight: 300; | |
line-height: 33px; | |
-webkit-font-smoothing: antialiased; | |
} | |
.line{ | |
fill: none; | |
stroke: #000; | |
stroke-width: 4px; | |
} | |
.circle{ | |
fill-opacity: 0.5; | |
} | |
.box{ | |
fill:#ecf0f1; | |
stroke: #2c3e50; | |
stroke-dasharray: 2px,2px; | |
} | |
.axis path, | |
.axis line { | |
fill: none; | |
stroke: none; | |
shape-rendering: crispEdges; | |
} | |
</style> | |
<body> | |
<script src="//d3js.org/d3.v3.min.js"></script> | |
<script> | |
var margin = { top: 60, right: 40, bottom: 60, left: 80 }, | |
width = 960 - margin.left - margin.right, | |
height = 640 - margin.top - margin.bottom; | |
bbox = {h: height , w: width, mt: 0} | |
var duration = 50, | |
maxRadius = 32, // maximum radius of circle | |
padding = 0.5, // padding between circles; also minimum radius | |
k = 1, // initial number of candidates to consider per circle | |
m = 5, // initial number of circles to add per frame | |
n = 280, // remaining number of circles to add | |
step = 0, | |
count = 0, | |
data = d3.range(2).map(function(d,i) { return {x:0, y:0}; }); | |
newCircle = bestCircleGenerator(maxRadius, padding, bbox.w, bbox.h, bbox.mt); | |
var x = d3.scale.linear().domain([0, n]).range([0, width]); | |
var y = d3.scale.linear().domain([0, 0.4]).range([height, 0]); | |
var color = d3.scale.threshold().domain([maxRadius*0.33, maxRadius*0.66, maxRadius]).range(['#2ecc71', '#f1c40f', '#e74c3c']); | |
var line = d3.svg.line().interpolate("basis") | |
.x(function(d, i) { return x(d.x); }) | |
.y(function(d, i) { return y(d.y); }); | |
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("rect") | |
.attr("width", bbox.w) | |
.attr("height", bbox.h) | |
.attr('y', bbox.mt) | |
.attr('class', 'box'); | |
var yaxis = svg.append("g") | |
.attr("class", "y axis") | |
.call(y.axis = d3.svg.axis().scale(y).orient("left").ticks(5)) | |
.append("text") | |
.attr("class", "label") | |
.attr("transform", "rotate(-90)") | |
.attr("y", -56) | |
.attr("dy", ".71em") | |
.style("text-anchor", "end") | |
.text("Ratio of Total Circle Area to Total Graph Area") | |
var g = svg.append('g') | |
var path = svg.append("path") | |
.datum(data) | |
.attr("class", "line"); | |
function tick(){ | |
var interval = setInterval(function() { | |
var rlast = 0; | |
for (var i = 0; i < m && --n >= 0; ++i) { | |
step+=1 | |
var circle = newCircle(k, step); | |
if (circle[0]){ // if a new circle was returned | |
g.append("circle") | |
.attr('class', 'circle') | |
.attr("cx", circle[0]) | |
.attr("cy", circle[1]) | |
.attr("r", 0) | |
.style("fill", color(circle[2])) | |
.transition() | |
.attr("r", circle[2]); | |
// Update our count. Note: some of the area extends beyond the box, which is okay. | |
count += circle[2]*circle[2]*Math.PI | |
if (rlast <= circle[2]){ | |
rlast = circle[2] | |
} else{ | |
n = 0 | |
} | |
// update the line every 5 circles to limit DOM manipulation. | |
if (step % 2 == 0) { | |
// update data | |
data.push({x: step, y: count/ (bbox.w * bbox.h)}); | |
// redraw the line | |
path.attr("d", line) | |
} | |
} | |
// As we add more circles, generate more candidates per circle. | |
// Since this takes more effort, gradually reduce circles per frame. | |
if (k < 500) k *= 1.1, m *= .998; | |
} | |
if(n < 0){ | |
console.log('restart') | |
clearInterval(interval); | |
setTimeout(function(){ | |
// Reset parameters | |
newCircle = bestCircleGenerator(maxRadius, padding, bbox.w, bbox.h, bbox.mt); | |
data = d3.range(2).map(function(d,i) { return {x:0, y:0}; }), | |
n = 280, step = 0, count = 0, k = 1, m = 5; | |
d3.selectAll('circle').transition().remove() | |
d3.selectAll('.line').transition().remove() | |
path = svg.append("path").datum(data).attr("class", "line"); | |
tick(); | |
}, 1500) | |
} | |
}, duration); | |
} | |
// See, http://bl.ocks.org/mbostock/6224050 | |
function bestCircleGenerator(maxRadius, padding, w, h, topmargin) { | |
var quadtree = d3.geom.quadtree().extent([[0, 0], [w, h]])([]), | |
searchRadius = maxRadius * 2, | |
maxRadius2 = maxRadius * maxRadius, | |
topmargin = topmargin || 0; | |
return function(k, step) { | |
var bestX, bestY, bestDistance = padding; | |
for (var i = 0; i < k; ++i) { | |
var x = Math.random() * w, | |
y = Math.random() * h + topmargin, | |
rx1 = x - searchRadius, | |
rx2 = x + searchRadius, | |
ry1 = y - searchRadius, | |
ry2 = y + searchRadius; | |
var minDistance = 2*Math.exp(step*0.01); | |
quadtree.visit(function(quad, x1, y1, x2, y2) { | |
if (p = quad.point) { | |
var p, | |
dx = x - p[0], | |
dy = y - p[1], | |
d2 = dx * dx + dy * dy, | |
r2 = p[2] * p[2]; | |
if (d2 < r2) return minDistance = 0, true; | |
var d = Math.sqrt(d2) - p[2]; | |
if (d < minDistance) minDistance = d; | |
} | |
return !minDistance || x1 > rx2 || x2 < rx1 || y1 > ry2 || y2 < ry1; | |
}); | |
if (minDistance > bestDistance) bestX = x, bestY = y, bestDistance = minDistance; | |
} | |
var best = [bestX, bestY, bestDistance - padding]; | |
quadtree.add(best); | |
return best; | |
}; | |
} | |
tick() | |
d3.select(self.frameElement).style("height", (height + margin.top + margin.bottom) + "px"); | |
</script> |
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