Pie charts labels

This variation of a donut chart demonstrates how to add labels with lines. Clicking on the button changes the displayed data. Check Pie Chart with Labels and Missing Data to see how to handle transitions with missing/new data.

forked from dbuezas's block: Pie charts labels

forked from dguardia's block: Pie charts labels

<!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>
<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.ordinal()
	.domain(["Lorem ipsum", "dolor sit"])
	.range(["#98abc5", "#8a89a6"]);

function randomData (){
	var labels = color.domain();
	return labels.map(function(label){
		return { label: label, value: Math.random() }
	});
}

change(randomData());

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

function change(data) {

/* ------- PIE SLICES -------*/
	var slice = svg.select(".slices").selectAll("path.slice")
		.data(pie(data), key);

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

slice		
		.transition().duration(1000)
		.attrTween("d", function(d) {
			this._current = this._current || d;
			var interpolate = d3.interpolate(this._current, d);
			this._current = interpolate(0);
			return function(t) {
				return arc(interpolate(t));
			};
		})

slice.exit()
		.remove();

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

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

text.enter()
		.append("text")
		.attr("dy", ".35em")
		.text(function(d) {
			return d.data.label;
		});
	
	function midAngle(d){
		return d.startAngle + (d.endAngle - d.startAngle)/2;
	}

text.transition().duration(1000)
		.attrTween("transform", function(d) {
			this._current = this._current || d;
			var interpolate = d3.interpolate(this._current, d);
			this._current = interpolate(0);
			return function(t) {
				var d2 = interpolate(t);
				var pos = outerArc.centroid(d2);
				pos[0] = radius * (midAngle(d2) < Math.PI ? 1 : -1);
				return "translate("+ pos +")";
			};
		})
		.styleTween("text-anchor", function(d){
			this._current = this._current || d;
			var interpolate = d3.interpolate(this._current, d);
			this._current = interpolate(0);
			return function(t) {
				var d2 = interpolate(t);
				return midAngle(d2) < Math.PI ? "start":"end";
			};
		});

text.exit()
		.remove();

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

var polyline = svg.select(".lines").selectAll("polyline")
		.data(pie(data), key);
	
	polyline.enter()
		.append("polyline");

polyline.transition().duration(1000)
		.attrTween("points", function(d){
			this._current = this._current || d;
			var interpolate = d3.interpolate(this._current, d);
			this._current = interpolate(0);
			return function(t) {
				var d2 = interpolate(t);
				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.exit()
		.remove();
};

</script>
</body>

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

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