Animating D3 donut chart on load - animation

Question

I have a donut chart with five different arcs inside of it. The data will not be updated but I want to have a transition of the whole graph being drawn as a circle when the page loads, starting at the selected angle (in my case 1.1*PI). Here is the jsfiddle of the graph: http://jsfiddle.net/Nw62g/
var data = [
{name: "one", value: 10375},
{name: "two", value: 7615},
{name: "three", value: 832},
{name: "four", value: 516},
{name: "five", value: 491}
];
var margin = {top: 20, right: 20, bottom: 20, left: 20};
width = 400 - margin.left - margin.right;
height = width - margin.top - margin.bottom;
var chart = d3.select("body")
.append('svg')
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + ((width/2)+margin.left) + "," +
((height/2)+margin.top) + ")");
var radius = Math.min(width, height) / 2;
var color = d3.scale.ordinal()
.range(["#3399FF", "#5DAEF8", "#86C3FA", "#ADD6FB", "#D6EBFD"]);
var arc = d3.svg.arc()
.outerRadius(radius)
.innerRadius(radius - 20);
var pie = d3.layout.pie()
.sort(null)
.startAngle(1.1*Math.PI)
.endAngle(3.1*Math.PI)
.value(function(d) { return d.value; });
var g = chart.selectAll(".arc")
.data(pie(data))
.enter().append("g")
.attr("class", "arc");
g.append("path")
.style("fill", function(d) { return color(d.data.name); })
.attr("d", arc);
How would I go about achieving this result?

Answer 1

You can do this with an attribute tween:
.attrTween('d', function(d) {
var i = d3.interpolate(d.startAngle+0.1, d.endAngle);
return function(t) {
d.endAngle = i(t);
return arc(d);
}
});
This animates the segment from start to end angle. To do this across the entire circle, you can use delayed transitions:
.transition().delay(function(d, i) { return i * 500; }).duration(500)
Complete example here. You can adjust start segment, duration, etc to your liking.