arc_ordinal_theta.vg.json

{
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  "background": "white",
  "padding": 5,
  "width": 200,
  "height": 200,
  "style": "view",
  "data": [
    {
      "name": "source_0",
      "values": [
        {"dir": "1N", "strength": 1},
        {"dir": "2NE", "strength": 2},
        {"dir": "3E", "strength": 3},
        {"dir": "4SE", "strength": 4},
        {"dir": "5S", "strength": 5},
        {"dir": "6SW", "strength": 6},
        {"dir": "7W", "strength": 7},
        {"dir": "8NW", "strength": 8}
      ]
    },
    {
      "name": "data_0",
      "source": "source_0",
      "transform": [
        {
          "type": "stack",
          "groupby": ["dir"],
          "field": "strength",
          "sort": {"field": [], "order": []},
          "as": ["strength_start", "strength_end"],
          "offset": "zero"
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"strength\"]) && isFinite(+datum[\"strength\"])"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "marks",
      "type": "arc",
      "style": ["arc"],
      "from": {"data": "data_0"},
      "encode": {
        "update": {
          "fill": {"scale": "color", "field": "dir"},
          "description": {
            "signal": "\"dir: \" + (isValid(datum[\"dir\"]) ? datum[\"dir\"] : \"\"+datum[\"dir\"]) + \"; strength: \" + (format(datum[\"strength\"], \"\"))"
          },
          "x": {"signal": "width", "mult": 0.5},
          "y": {"signal": "height", "mult": 0.5},
          "outerRadius": {"scale": "radius", "field": "strength_end"},
          "innerRadius": {"scale": "radius", "field": "strength_start"},
          "startAngle": {"scale": "theta", "field": "dir"},
          "endAngle": {
            "scale": "theta",
            "field": "dir",
            "offset": {"signal": "bandwidth('theta')"}
          }
        }
      }
    }
  ],
  "scales": [
    {
      "name": "theta",
      "type": "band",
      "domain": {"data": "data_0", "field": "dir", "sort": true},
      "range": [0, 6.283185307179586]
    },
    {
      "name": "radius",
      "type": "linear",
      "domain": {
        "data": "data_0",
        "fields": ["strength_start", "strength_end"]
      },
      "range": [0, {"signal": "min(width,height)/2"}],
      "zero": true
    },
    {
      "name": "color",
      "type": "ordinal",
      "domain": {"data": "data_0", "field": "dir", "sort": true},
      "range": "category"
    }
  ],
  "legends": [{"fill": "color", "symbolType": "circle", "title": "dir"}],
  "config": {"style": {"tick": {"discreteBandSize": {"band": 0.75}}}}
}