{
  "$schema": "urn:prism:schema:v1:spec",
  "title": "Hierarchical clustering dendrogram",
  "data": {
    "name": "clusters",
    "values": [
      {"id": "root", "parent": null,   "name": "all"},
      {"id": "a",    "parent": "root", "name": "cluster a"},
      {"id": "b",    "parent": "root", "name": "cluster b"},
      {"id": "a1",   "parent": "a",    "name": "alpha"},
      {"id": "a2",   "parent": "a",    "name": "beta"},
      {"id": "b1",   "parent": "b",    "name": "gamma"},
      {"id": "b2",   "parent": "b",    "name": "delta"},
      {"id": "b3",   "parent": "b",    "name": "epsilon"}
    ]
  },
  "mark": {"type": "dendrogram"},
  "encoding": {
    "source": {"field": "parent"},
    "target": {"field": "id"},
    "text":   {"field": "name"}
  }
}