fold_donut

fold_donut.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [
      {"category": "A", "subcategory": "A1", "sales": 100},
      {"category": "A", "subcategory": "A2", "sales": 200},
      {"category": "B", "subcategory": "B1", "sales": 150},
      {"category": "B", "subcategory": "B2", "sales": 50}
    ]
  },
  "transform": [
    {"fold": ["category", "subcategory"], "as": ["Type", "Name"]},
    {
      "calculate": "datum.Type === 'category' ? datum.sales : 0",
      "as": "CategorySales"
    },
    {
      "calculate": "datum.Type === 'subcategory' ? datum.sales : 0",
      "as": "SubcategorySales"
    }
  ],
  "layer": [
    {
      "mark": {"type": "arc", "innerRadius": 80, "outerRadius": 100},
      "encoding": {
        "theta": {"field": "CategorySales", "type": "quantitative"},
        "color": {"field": "Name", "type": "nominal"}
      }
    },
    {
      "mark": {"type": "arc", "innerRadius": 60, "outerRadius": 75},
      "encoding": {
        "theta": {"field": "SubcategorySales", "type": "quantitative"},
        "color": {"field": "Name", "type": "nominal"}
      }
    }
  ]
}