Sankey diagram

Use a sankey diagram to show how a quantity splits and merges as it moves from where it starts to where it ends, such as energy, money or visitors.

Source

```chart
type: sankey
title: Coal and gas feed most of the power that homes and industry use
subtitle: Energy flows in TWh, synthetic
data:
  inline:
    - {from: Coal, to: Power, twh: 35}
    - {from: Gas, to: Power, twh: 30}
    - {from: Gas, to: Heat, twh: 25}
    - {from: Wind, to: Power, twh: 20}
    - {from: Solar, to: Power, twh: 10}
    - {from: Power, to: Homes, twh: 45}
    - {from: Power, to: Industry, twh: 40}
    - {from: Power, to: Losses, twh: 10}
    - {from: Heat, to: Homes, twh: 15}
    - {from: Heat, to: Industry, twh: 10}
encoding: {source: from, target: to, y: twh}
axes:
  y: {label: TWh}
```

Fields that matter

• type: sankey with encoding.source for the node a flow starts at, encoding.target for the node it ends at and encoding.y for its value; each pair of nodes may have one row
• A node stands in the column of its longest path from a source, and is as tall as the larger of what enters and what leaves it
• A ribbon is as wide as its flow; ribbons and nodes take the colour of the source that a node mostly receives from, and the legend names the sources
• A flow that points back and closes a cycle is left out with a finding, so what is drawn flows one way; rows without a node, with a missing or negative value, or with a value of zero are left out and counted
• A sankey takes at most 300 nodes and 2,000 links in a panel; above that the chart is not drawn and check raises chart.limit-exceeded naming the limit and the count
• Node sizes, shares and the sides of a node are computed by RichView and marked as derived in the readout
• encoding.facet makes one diagram per value on a shared scale unless style.facet_scale is free; names that do not fit beside their node are left out and listed

Interactions

• Hover or focus a node to read its size, what enters and leaves it and its share of the column.
• Hover or focus a ribbon to read its value and its share of its source and of its target.
• Click a legend entry to remove a source and what it feeds, and back.
• Open the Table view, Download PNG or CSV, or Expand the chart.