Pie Chart Labels with missing data

This variation of a donut chart demonstrates how to add labels with lines and also works with missing/new data. Clicking on the button changes the displayed data.

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  width: 960px;
  height: 500px;
  position: relative;
}
svg{
	width: 100%;
	height: 100%;
}
path.slice{
	stroke-width:2px;
}

polyline{
	opacity: .3;
	stroke: black;
	stroke-width: 2px;
	fill: none;
}

</style>
<body>
Duration: 0<input type="range" id="duration" min="0" max="5000">5000 
<br>
<button class="randomize">randomize</button>

var svg = d3.select("body")
	.append("svg")
	.append("g")

svg.append("g")
	.attr("class", "slices");
svg.append("g")
	.attr("class", "labels");
svg.append("g")
	.attr("class", "lines");

var width = 960,
    height = 450,
	radius = Math.min(width, height) / 2;

var pie = d3.layout.pie()
	.sort(null)
	.value(function(d) {
		return d.value;
	});

var arc = d3.svg.arc()
	.outerRadius(radius * 0.8)
	.innerRadius(radius * 0.4);

var outerArc = d3.svg.arc()
	.innerRadius(radius * 0.9)
	.outerRadius(radius * 0.9);

svg.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");

var key = function(d){ return d.data.label; };

var color = d3.scale.category20()
	.domain(["Lorem ipsum", "dolor sit", "amet", "consectetur", "adipisicing", "elit", "sed", "do", "eiusmod", "tempor", "incididunt"])
	//.range(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56", "#d0743c", "#ff8c00"]);

change(randomData());

d3.select(".randomize")
	.on("click", function(){
		change(randomData());
	});

function mergeWithFirstEqualZero(first, second){
	var secondSet = d3.set(); second.forEach(function(d) { secondSet.add(d.label); });

function change(data) {
	var duration = +document.getElementById("duration").value;
	var data0 = svg.select(".slices").selectAll("path.slice")
		.data().map(function(d) { return d.data });
	if (data0.length == 0) data0 = data;
	var was = mergeWithFirstEqualZero(data, data0);
	var is = mergeWithFirstEqualZero(data0, data);

/* ------- SLICE ARCS -------*/

var slice = svg.select(".slices").selectAll("path.slice")
		.data(pie(was), key);

slice.enter()
		.insert("path")
		.attr("class", "slice")
		.style("fill", function(d) { return color(d.data.label); })
		.each(function(d) {
			this._current = d;
		});

slice = svg.select(".slices").selectAll("path.slice")
		.data(pie(is), key);

slice		
		.transition().duration(duration)
		.attrTween("d", function(d) {
			var interpolate = d3.interpolate(this._current, d);
			var _this = this;
			return function(t) {
				_this._current = interpolate(t);
				return arc(_this._current);
			};
		});

slice = svg.select(".slices").selectAll("path.slice")
		.data(pie(data), key);

slice
		.exit().transition().delay(duration).duration(0)
		.remove();

/* ------- TEXT LABELS -------*/

var text = svg.select(".labels").selectAll("text")
		.data(pie(was), key);

text.enter()
		.append("text")
		.attr("dy", ".35em")
		.style("opacity", 0)
		.text(function(d) {
			return d.data.label;
		})
		.each(function(d) {
			this._current = d;
		});
	
	function midAngle(d){
		return d.startAngle + (d.endAngle - d.startAngle)/2;
	}

text = svg.select(".labels").selectAll("text")
		.data(pie(is), key);

text.transition().duration(duration)
		.style("opacity", function(d) {
			return d.data.value == 0 ? 0 : 1;
		})
		.attrTween("transform", function(d) {
			var interpolate = d3.interpolate(this._current, d);
			var _this = this;
			return function(t) {
				var d2 = interpolate(t);
				_this._current = d2;
				var pos = outerArc.centroid(d2);
				pos[0] = radius * (midAngle(d2) < Math.PI ? 1 : -1);
				return "translate("+ pos +")";
			};
		})
		.styleTween("text-anchor", function(d){
			var interpolate = d3.interpolate(this._current, d);
			return function(t) {
				var d2 = interpolate(t);
				return midAngle(d2) < Math.PI ? "start":"end";
			};
		});
	
	text = svg.select(".labels").selectAll("text")
		.data(pie(data), key);

text
		.exit().transition().delay(duration)
		.remove();

/* ------- SLICE TO TEXT POLYLINES -------*/

var polyline = svg.select(".lines").selectAll("polyline")
		.data(pie(was), key);
	
	polyline.enter()
		.append("polyline")
		.style("opacity", 0)
		.each(function(d) {
			this._current = d;
		});

polyline = svg.select(".lines").selectAll("polyline")
		.data(pie(is), key);
	
	polyline.transition().duration(duration)
		.style("opacity", function(d) {
			return d.data.value == 0 ? 0 : .5;
		})
		.attrTween("points", function(d){
			this._current = this._current;
			var interpolate = d3.interpolate(this._current, d);
			var _this = this;
			return function(t) {
				var d2 = interpolate(t);
				_this._current = d2;
				var pos = outerArc.centroid(d2);
				pos[0] = radius * 0.95 * (midAngle(d2) < Math.PI ? 1 : -1);
				return [arc.centroid(d2), outerArc.centroid(d2), pos];
			};			
		});
	
	polyline = svg.select(".lines").selectAll("polyline")
		.data(pie(data), key);
	
	polyline
		.exit().transition().delay(duration)
		.remove();
};

</script>
</body>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js