Sankey flow diagram

Show flows between nodes laid out in columns — sources on the left, sinks on the right, intermediate nodes in between. Ribbon thickness encodes flow magnitude. Useful for conversion funnels, budget allocation, energy flow, attribution.

The demo plots the NASA astronaut career flow, Groups 1–3 (Mercury / Gemini / Apollo eras). ~30 astronauts; sources on the left are the service branches they came from (USAF, Navy / USMC); the middle column groups them by training cohort (Mercury or Gemini); the right shows the ultimate Apollo outcome (Walked on Moon vs Did not). Twelve astronauts ultimately walked on the Moon — the right-hand ribbon converging into that node is the visible bottom-line of the whole program.

Source: NASA Astronaut Group 1 — Wikipedia

Public surface

use wisp_chart::topology::{Sankey, SankeyLink, SankeyNode};

let nodes = vec![
    SankeyNode::new("Organic",   /* column */ 0, blue),
    SankeyNode::new("Paid",      0, orange),
    SankeyNode::new("Signed Up", 1, green),
    SankeyNode::new("Trial",     1, pink),
    SankeyNode::new("Converted", 2, sky),
    SankeyNode::new("Lost",      2, gold),
];
let links = vec![
    SankeyLink::new(0, 2, 40.0, grey),
    SankeyLink::new(0, 3, 25.0, grey),
    // ...
];
let s = Sankey::new(nodes, links);
let g = s.emit_graphics(&theme, viewport);