D3 v4 Basic Pie Chart

Adapted from tutorial on http://www.cagrimmett.com/

A simple pie chart.

gh-pages demo

• The first Pie Chart counts the number of each category that exist.

var category_count = d3.nest()
  .key(function(d) {
    return d.category;
  })
  .rollup(function(leaves) {
    return leaves.length;
  })
  .entries(data);

var category_arcs = d3.pie()
  .value(function(d) {
    return d.value;
  })
  (category_count);

• The second Pie Chart sums the value in each category.

var category_sum = d3.nest().key(function(d) {
    return d.category;
  })
  .rollup(function(leaves) {
    return d3.sum(leaves, function(d) {
      return d.value;
    });
  }).entries(data)
  .map(function(d) {
    return {
      Category: d.key,
      totalValue: d.value
    };
  });

var category_sum_arcs = d3.pie()
  .value(function(d) {
    return d.totalValue;
  })
  (category_sum);