var data = [

    {name: "Sample1", val: 2000},

    {name: "Sample2", val: 100},

    {name: "Sample3", val: 800},

    {name: "Sample4", val: 400},

    {name: "Sample5", val: 200}

];

​

var margin = {top: 40, right: 40, bottom: 40, left: 40};

​

var w = 600 - margin.left - margin.right,

    h = 400 - margin.top - margin.bottom,

    r = Math.min(w, h) / 2,

    labelr = r + 20, // radius for label anchor

    donut = d3.layout.pie().sort(null),

    inner = r * 0.6,

    arc = d3.svg.arc().innerRadius(inner).outerRadius(r),

    arcOver = d3.svg.arc().innerRadius(inner + 5).outerRadius(r + 5);

​

var color = d3.scale.category20c();

​

var total = d3.sum(data, function(d) { return d3.sum(d3.values(d));});

​

var vis = d3.select("body")

    .append("svg")

    .data([data])

    .attr("width", w + margin.left + margin.right)

    .attr("height", h + margin.top + margin.bottom);

​

var textTop = vis.append("text")

    .attr("dy", ".35em")

    .style("text-anchor", "middle")

    .attr("font-family", "Segoe UI")

    .attr("font-size", r/7 + "px")

    .attr("fill", "#bbb")

    .attr("x", (w + margin.left + margin.right) / 2)

    .attr("y", ((h + margin.top + margin.bottom) / 2) - (r/7)/2)

    .text("TOTAL");

​

var textBottom = vis.append("text")

    .attr("dy", ".35em")

    .attr("font-family", "Segoe UI")

    .style("text-anchor", "middle")

    .attr("font-weight", "bold")

    .attr("font-size", r/6 + "px")

    .text(total)

    .attr("x", (w + margin.left + margin.right) / 2)

    .attr("y", ((h + margin.top + margin.bottom) / 2) + (r/6)/2);

​

var arcs = vis.selectAll("arc")

    .data(donut.value(function(d) { return d.val;}))

    .enter().append("g")

    .attr("class", "arc")

    .attr("transform", "translate(" + (w + margin.left + margin.right) / 2 + "," + (h + margin.top + margin.bottom) / 2 + ")");

​

arcs.append("path")

    .attr("fill", function(d) { return color(d.data.name); })

    .attr("d", arc)

    .style("stroke", "white")

    .style("stroke-width", 2);

​

arcs.append("text")

    .attr("transform", function(d) {

        var c = arc.centroid(d),

            x = c[0],

            y = c[1],

            // pythagorean theorem for hypotenuse

            h = Math.sqrt(x*x + y*y);

        return "translate(" + (x/h * labelr) +  ',' +

           (y/h * labelr) +  ")";

    })

    .attr("dy", ".35em")

    .attr("text-anchor", function(d) {

        // are we past the center?

        return (d.endAngle + d.startAngle)/2 > Math.PI ?

            "end" : "start";

    })

    .text(function(d) { return d.data.name; });

​

arcs.selectAll("path")

    .on("mouseover", function(d){

      d3.select(this).transition()

        .duration(200)

        .attr("d", arcOver);

​

      textTop.text(d.data.name);

      textBottom.text(d.data.val);

      d3.select(this).style("fill", "red");

      /*

      var fontSize = r/3.5;

      var xPos = (w + margin.left + margin.right) / 2;

      var yPos = ((h + margin.top + margin.bottom) / 2) + fontSize / 2;

      vis.append("text")

        .attr("x", xPos)

        .attr("y", yPos)

        .attr("id", "tooltip")

        .style("text-anchor", "middle")

        .attr("font-weight", "bold")

        .attr("font-size", fontSize + "px")

        .style("fill", "black")

        .text(d.data.val);

      */

    })

    .on("mouseout", function(){

      d3.select(this).transition()

        .duration(100)

        .attr("d", arc);

      //vis.selectAll("#tooltip").remove();

      d3.select(this).style("fill", function(d) { return color(d.data.name); });

      textTop.text("TOTAL");

      textBottom.text(total);

    });

​

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

  .attr("id", "legend")

  .attr("width", r)

  .attr("height", r * 2)

  .selectAll("g")

  .data(color.domain().slice())

  .enter().append("g")

  .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });

​

legend.append("rect")

  .attr("width", 18)

  .attr("height", 18)

  .style("fill", color);

​

legend.append("text")

  .attr("x", 24)

  .attr("y", 9)

  .attr("dy", ".35em")

  .text(function(d) { return d;});