{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "A quantile-quantile plot example, comparing distributions by quantile values.",
  "padding": 5,

  "signals": [
    { "name": "plotWidth", "value": 250 },
    { "name": "height", "update": "plotWidth" },
    {
      "name": "numQuantiles", "value": 100,
      "bind": {"input": "range", "min": 20, "max": 200, "step": 1}
    },
    {
      "name": "url",
      "value": "data/normal-2d.json",
      "bind": {
        "input": "select",
        "options": [
          "data/normal-2d.json",
          "data/uniform-2d.json"
        ]
      }
    }
  ],

  "data": [
    {
      "name": "points",
      "url": {"signal": "url"}
    },
    {
      "name": "quantiles",
      "source": "points",
      "transform": [
        {
          "type": "quantile",
          "field": "u",
          "step": {"signal": "1 / (numQuantiles + 1)"}
        },
        {
          "type": "formula",
          "as": "quniform",
          "expr": "quantileUniform(datum.prob)"
        },
        {
          "type": "formula",
          "as": "qnormal",
          "expr": "quantileNormal(datum.prob)"
        }
      ]
    }
  ],

  "scales": [
    {
      "name": "y",
      "domain": {"data": "points", "field": "u"},
      "range": "height",
      "nice": true
    }
  ],

  "layout": {
    "columns": 2,
    "padding": 10
  },

  "marks": [
    {
      "type": "group",
      "encode": {
        "update": {
          "width": {"signal": "plotWidth"},
          "height": {"signal": "plotWidth"}
        }
      },
      "signals": [
        {"name": "width", "update": "plotWidth"}
      ],
      "scales": [
        {
          "name": "x",
          "domain": [0, 1],
          "range": "width"
        }
      ],
      "axes": [
        {
          "scale": "y",
          "orient": "left",
          "offset": 10,
          "grid": true,
          "title": "Empirical Data Quantiles"
        },
        {
          "scale": "x",
          "orient": "bottom",
          "grid": true,
          "title": "Theoretical Uniform Quantiles"
        }
      ],
      "marks": [
        {
          "type": "symbol",
          "from": {"data": "quantiles"},
          "encode": {
            "update": {
              "x": {"scale": "x", "field": "quniform"},
              "y": {"scale": "y", "field": "value"},
              "fill": {"value": "steelblue"},
              "size": {"value": 16}
            }
          }
        }
      ]
    },
    {
      "type": "group",
      "encode": {
        "update": {
          "width": {"signal": "plotWidth"},
          "height": {"signal": "plotWidth"}
        }
      },
      "signals": [
        {"name": "width", "update": "plotWidth"}
      ],
      "scales": [
        {
          "name": "x",
          "domain": [-3, 3],
          "range": "width"
        }
      ],
      "axes": [
        {
          "scale": "y",
          "orient": "left",
          "domain": false, "labels": false, "ticks": false, "grid": true
        },
        {
          "scale": "x",
          "orient": "bottom",
          "grid": true,
          "title": "Theoretical Normal Quantiles"
        }
      ],
      "marks": [
        {
          "type": "symbol",
          "from": {"data": "quantiles"},
          "encode": {
            "update": {
              "x": {"scale": "x", "field": "qnormal"},
              "y": {"scale": "y", "field": "value"},
              "fill": {"value": "steelblue"},
              "size": {"value": 16}
            }
          }
        }
      ]
    }
  ]
}
