Got mad stacks

The stack layout allows us to stack regions in a chart, which is useful for things such as stacked area charts and what have you. It's in the d3-shape package.

Go back to main.js and comment out the last example and add the following:

westerosChart.init('stack',
  'data/GoT-deaths-by-season.json', false);

We add another option to this because we're going to create two charts from this example. This time we're using our deaths-by-season dataset.

Inchapter7/index.js add the following to the bottom of the file:

westerosChart.stack = function Stack({ data }, isStream = false) { 
  const episodesPerSeason = 10; 
  const totalSeasons = 6; 
  // Create a nest containing deaths per episode
  const seasons = d3.nest() 
    .key(d => d.death.episode) 
    .key(d => d.death.season) 
    .entries(data.filter(d => !d.death.isFlashback)) 
    .map(v => { 
      return d3.range(1, totalSeasons + 1)
        .reduce((item, episodeNumber) => { 
          const deaths = v.values.filter...