 "r0", "a1", "r1", "depth", "children"],
              "type": "partition",
              "size": [{ "signal": "width" }, { "signal": "height" }],
              "padding": 2,
              "sort": { "field": "id" }
            }
          ]
        }
      ]
    }

    var spec = {
      "$schema": "https://vega.github.io/schema/vega/v5.json",
      "description": "An example of treemap layout for hierarchical data.",
      "width": 960,
      "height": 500,
      "padding": 2.5,
      "autosize": "none",

