{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "width": 500,
  "padding": 5,

  "signals": [
    { "name": "plotHeight", "value": 50 },
    { "name": "bandwidth", "value": 0,
      "bind": {"input": "range", "min": 0, "max": 1, "step": 0.01} }
  ],

  "data": [
    {
      "name": "points",
      "values": [
        {"k": "a", "v": 1}, {"k": "a", "v": 3}, {"k": "a", "v": 3}, {"k": "a", "v": 5},
        {"k": "b", "v": 2}, {"k": "b", "v": 2}, {"k": "b", "v": 4}
      ]
    },
    {
      "name": "pdf",
      "source": "points",
      "transform": [
        {
          "type": "kde",
          "groupby": ["k"],
          "field": "v",
          "bandwidth": {"signal": "bandwidth"}
        }
      ]
    },
    {
      "name": "cdf",
      "source": "points",
      "transform": [
        {
          "type": "kde",
          "cumulative": true,
          "groupby": ["k"],
          "field": "v",
          "bandwidth": {"signal": "bandwidth"}
        }
      ]
    }
  ],

  "scales": [
    {
      "name": "xscale",
      "type": "linear",
      "range": "width",
      "domain": {"data": "points", "field": "v"},
      "zero": false,
      "nice": true
    },
    {
      "name": "ypdf",
      "type": "linear",
      "range": [{"signal": "plotHeight"}, 0],
      "domain": {"data": "pdf", "field": "density"}
    },
    {
      "name": "ycdf",
      "type": "linear",
      "range": [{"signal": "plotHeight"}, 0],
      "domain": {"data": "cdf", "field": "density"}
    }
  ],

  "layout": {
    "columns": 1,
    "padding": 10
  },

  "marks": [
    {
      "type": "group",
      "from": {
        "facet": {
          "data": "pdf",
          "name": "facet",
          "groupby": "k"
        }
      },
      "encode": {
        "enter": {
          "height": {"signal": "plotHeight"}
        }
      },
      "axes": [
        {"orient": "bottom", "scale": "xscale", "zindex": 1}
      ],
      "marks": [
        {
          "type": "area",
          "from": {"data": "facet"},
          "encode": {
            "update": {
              "x": {"scale": "xscale", "field": "value"},
              "y": {"scale": "ypdf", "field": "density"},
              "y2": {"scale": "ypdf", "value": 0},
              "fill": {"value": "steelblue"}
            }
          }
        }
      ]
    },
    {
      "type": "group",
      "from": {
        "facet": {
          "data": "cdf",
          "name": "facet",
          "groupby": "k"
        }
      },
      "encode": {
        "enter": {
          "height": {"signal": "plotHeight"}
        }
      },
      "axes": [
        {"orient": "bottom", "scale": "xscale", "zindex": 1}
      ],
      "marks": [
        {
          "type": "area",
          "from": {"data": "facet"},
          "encode": {
            "update": {
              "x": {"scale": "xscale", "field": "value"},
              "y": {"scale": "ycdf", "field": "density"},
              "y2": {"scale": "ycdf", "value": 0},
              "fill": {"value": "steelblue"}
            }
          }
        }
      ]
    }
  ]
}