Area Chart (Vega)

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "An area chart example.",
  "width": 400,
  "height": 200,
  "padding": 5,

  "data": [
    {
      "name": "table",
      "values": [
        {"date": "2024-01-01", "value": 28},
        {"date": "2024-02-01", "value": 55},
        {"date": "2024-03-01", "value": 43},
        {"date": "2024-04-01", "value": 91},
        {"date": "2024-05-01", "value": 81},
        {"date": "2024-06-01", "value": 53},
        {"date": "2024-07-01", "value": 19},
        {"date": "2024-08-01", "value": 87}
      ],
      "transform": [
        {
          "type": "formula",
          "expr": "toDate(datum.date)",
          "as": "date"
        }
      ]
    }
  ],

  "scales": [
    {
      "name": "xscale",
      "type": "time",
      "domain": {"data": "table", "field": "date"},
      "range": "width"
    },
    {
      "name": "yscale",
      "type": "linear",
      "domain": {"data": "table", "field": "value"},
      "nice": true,
      "range": "height"
    }
  ],

  "axes": [
    {"orient": "bottom", "scale": "xscale", "format": "%b %Y"},
    {"orient": "left", "scale": "yscale"}
  ],

  "marks": [
    {
      "type": "area",
      "from": {"data": "table"},
      "encode": {
        "enter": {
          "x": {"scale": "xscale", "field": "date"},
          "y": {"scale": "yscale", "field": "value"},
          "y2": {"scale": "yscale", "value": 0},
          "fill": {"value": "steelblue"},
          "fillOpacity": {"value": 0.5}
        }
      }
    }
  ]
}