Metis Unemployment Rate Bar Chart Nesting and Labels Example

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
    .bartext {
      fill: white;
      font: 20px Helvetica, Verdana, Tahoma;
    }
  </style>
</head>

var margin = {top: 10, right: 20, bottom: 20, left: 60},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var y = d3.scaleLinear()
        .rangeRound([height, 0]);

var x = d3.scaleBand()
    .rangeRound([0, width])
    .paddingInner(0.05)
    .align(0.1);

var g = d3.select("svg")
          .append("g")
          .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

g.append("text")
     .attr("x", 125)
     .attr("y", 20)
     .style("font-size", "25px")
     .style("text-decoration", "underline")
     .text("Average United States Unemployment Rate (%) 2017 by Subregion")

d3.csv("us-unemployment-2017.csv", function(data) {
     console.log('Original data', data);
     var averageUnemploymentbySubregion = d3.nest().key(function(d) {return d.Subregion}).rollup(function(v) { return d3.mean(v, function(d) { return parseInt(d.Rate);}); }).entries(data);
     averageUnemploymentbySubregion.sort(function(a, b) { return b.value - a.value; });
     x.domain(averageUnemploymentbySubregion.map(function(d) { return d.key; }));
     y.domain([0, d3.max(averageUnemploymentbySubregion, function(d) { return d.value; })])

g.append("g")
     .attr("class", "axis")
     .attr("transform", "translate(0," + height + ")")
     .call(d3.axisBottom(x));

//  Append y-axis (optional)
    // g.append("g")
    //   .attr("class", "axis")
    //   .call(d3.axisLeft(y).ticks(null, "s"))

var bars = g.selectAll(".bar")
      .data(averageUnemploymentbySubregion)

var enter = bars.enter().append('g')

enter.append("rect")
        .attr("class", "bar")
        .attr("x", function(d) { return x(d.key); })
        .attr("y", function(d) { return y(d.value) })
        .attr("width", x.bandwidth())
        .attr("height", function(d) { return height - y(d.value); })
        .attr('fill', 'steelblue')

enter.append('text') // bound on the parent
         .attr("class", "bartext")

// enter + update
     // What's left on the screen once you've removed the extraneous.
     // Merge what is displayed -- what's added and what's remaining.
     // Add things that should be re-rendered with data change.
     bars = enter.merge(bars)

bars.select('text')
         // include x and y values to position the text
         .attr('x', function(d) { return x(d.key) + data.length/2})
         .attr('y', function(d) { return y(d.value) + 25} )
         .text(function(d){ return d.value.toFixed(1)})

// Grouping with D3 nest
    var groupedByRegion = d3.nest().key(function(d) {return d.Region}).entries(data);
    console.log('groupedByRegion', groupedByRegion);
    var groupedBySubRegion = d3.nest().key(function(d) {return d.Subregion}).entries(data);
    var groupedByState = d3.nest().key(function(d) {return d.StateName}).entries(data);
    console.log('groupedByState', groupedByState)

// Statistics
    var averageUnemploymentByRegion = d3.nest().key(function(d) {return d.Region}).rollup(function(v) { return d3.mean(v, function(d) { return parseInt(d.Rate);}); }).entries(data);
    var averageUnemploymentbySubregion = d3.nest().key(function(d) {return d.Subregion}).rollup(function(v) { return d3.mean(v, function(d) { return parseInt(d.Rate);}); }).entries(data);
    console.log('averageUnemploymentByRegion', averageUnemploymentByRegion);
    console.log('averageUnemploymentbySubregion', averageUnemploymentbySubregion);

});

</script>
</body>

https://d3js.org/d3.v4.min.js