Basic Sankey Diagram

Mix.install([
  {:plotly_ex, "~> 0.3"},
  {:kino, "~> 0.18"}
])

Section

Sankey.new/1 takes node: and link: as plain maps. node.label — list of node names. Nodes are referenced by zero-based index in link. link.source / link.target — index into the node list. link.value — flow magnitude.

alias Plotly.{Figure, Sankey}

Figure.new()
|> Figure.add_trace(
  Sankey.new(
    node: %{
      label: ["Coal", "Natural Gas", "Oil", "Electricity", "Losses"]
    },
    link: %{
      source: [0, 1, 2, 0, 1],
      target: [3, 3, 3, 4, 4],
      value:  [25, 20, 30, 10, 15]
    }
  )
)
|> Figure.update_layout(title: "Basic Sankey Diagram")
|> Plotly.show()

Reverse direction and preserve input order

Plotly.js v4 adds direction: "reversed" and node.sort / link.sort. Set both sorts to "input" to preserve the supplied ordering rather than letting the automatic arrangement sort the flows.

Figure.new()
|> Figure.add_trace(Sankey.new(
  direction: "reversed",
  node: %{label: ["Coal", "Natural Gas", "Electricity", "Losses"], sort: "input"},
  link: %{
    source: [0, 0, 1, 1], target: [2, 3, 2, 3],
    value: [25, 10, 20, 15], sort: "input"
  }
))
|> Figure.update_layout(title: "Reversed Sankey with input ordering")
|> Plotly.show()