{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "Drag the sliders to highlight points.",
  "background": "white",
  "padding": 5,
  "width": 200,
  "height": 200,
  "style": "cell",
  "data": [
    {
      "name": "CylYr_store",
      "values": [
        {
          "unit": "layer_0",
          "fields": [
            {"type": "E", "field": "Cylinders"},
            {"type": "E", "field": "Year"}
          ],
          "values": [4, 1977]
        }
      ]
    },
    {
      "name": "source_0",
      "url": "data/cars.json",
      "format": {"type": "json"},
      "transform": [
        {"type": "formula", "expr": "year(datum.Year)", "as": "Year"}
      ]
    },
    {
      "name": "data_0",
      "source": "source_0",
      "transform": [
        {
          "type": "filter",
          "expr": "isValid(datum[\"Horsepower\"]) && isFinite(+datum[\"Horsepower\"]) && isValid(datum[\"Miles_per_Gallon\"]) && isFinite(+datum[\"Miles_per_Gallon\"])"
        }
      ]
    },
    {
      "name": "data_1",
      "source": "source_0",
      "transform": [
        {
          "type": "filter",
          "expr": "!length(data(\"CylYr_store\")) || vlSelectionTest(\"CylYr_store\", datum)"
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"Horsepower\"]) && isFinite(+datum[\"Horsepower\"]) && isValid(datum[\"Miles_per_Gallon\"]) && isFinite(+datum[\"Miles_per_Gallon\"])"
        }
      ]
    }
  ],
  "signals": [
    {
      "name": "unit",
      "value": {},
      "on": [
        {"events": "mousemove", "update": "isTuple(group()) ? group() : unit"}
      ]
    },
    {
      "name": "CylYr_Year",
      "init": "1977",
      "bind": {"input": "range", "min": 1969, "max": 1981, "step": 1}
    },
    {
      "name": "CylYr_Cylinders",
      "init": "4",
      "bind": {"input": "range", "min": 3, "max": 8, "step": 1}
    },
    {
      "name": "CylYr",
      "update": "vlSelectionResolve(\"CylYr_store\", \"union\", true, true)"
    },
    {
      "name": "CylYr_tuple",
      "update": "CylYr_Cylinders !== null && CylYr_Year !== null ? {fields: CylYr_tuple_fields, values: [CylYr_Cylinders, CylYr_Year]} : null"
    },
    {
      "name": "CylYr_tuple_fields",
      "value": [
        {"type": "E", "field": "Cylinders"},
        {"type": "E", "field": "Year"}
      ]
    },
    {
      "name": "CylYr_modify",
      "on": [
        {
          "events": {"signal": "CylYr_tuple"},
          "update": "modify(\"CylYr_store\", CylYr_tuple, true)"
        }
      ]
    }
  ],
  "marks": [
    {
      "name": "layer_0_marks",
      "type": "symbol",
      "style": ["circle"],
      "interactive": true,
      "from": {"data": "data_0"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "fill": [
            {
              "test": "!length(data(\"CylYr_store\")) || vlSelectionTest(\"CylYr_store\", datum)",
              "scale": "color",
              "field": "Origin"
            },
            {"value": "grey"}
          ],
          "ariaRoleDescription": {"value": "circle"},
          "description": {
            "signal": "\"Horsepower: \" + (format(datum[\"Horsepower\"], \"\")) + \"; Miles_per_Gallon: \" + (format(datum[\"Miles_per_Gallon\"], \"\")) + \"; Origin: \" + (isValid(datum[\"Origin\"]) ? datum[\"Origin\"] : \"\"+datum[\"Origin\"])"
          },
          "x": {"scale": "x", "field": "Horsepower"},
          "y": {"scale": "y", "field": "Miles_per_Gallon"},
          "shape": {"value": "circle"}
        }
      }
    },
    {
      "name": "layer_1_marks",
      "type": "symbol",
      "style": ["circle"],
      "interactive": false,
      "from": {"data": "data_1"},
      "encode": {
        "update": {
          "opacity": {"value": 0.7},
          "fill": {"scale": "color", "field": "Origin"},
          "ariaRoleDescription": {"value": "circle"},
          "description": {
            "signal": "\"Horsepower: \" + (format(datum[\"Horsepower\"], \"\")) + \"; Miles_per_Gallon: \" + (format(datum[\"Miles_per_Gallon\"], \"\")) + \"; Origin: \" + (isValid(datum[\"Origin\"]) ? datum[\"Origin\"] : \"\"+datum[\"Origin\"])"
          },
          "x": {"scale": "x", "field": "Horsepower"},
          "y": {"scale": "y", "field": "Miles_per_Gallon"},
          "size": {"value": 100},
          "shape": {"value": "circle"}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "linear",
      "domain": {
        "fields": [
          {"data": "data_0", "field": "Horsepower"},
          {"data": "data_1", "field": "Horsepower"}
        ]
      },
      "range": [0, {"signal": "width"}],
      "nice": true,
      "zero": true
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {
        "fields": [
          {"data": "data_0", "field": "Miles_per_Gallon"},
          {"data": "data_1", "field": "Miles_per_Gallon"}
        ]
      },
      "range": [{"signal": "height"}, 0],
      "nice": true,
      "zero": true
    },
    {
      "name": "color",
      "type": "ordinal",
      "domain": {
        "fields": [
          {"data": "data_0", "field": "Origin"},
          {"data": "data_1", "field": "Origin"}
        ],
        "sort": true
      },
      "range": "category"
    }
  ],
  "axes": [
    {
      "scale": "x",
      "orient": "bottom",
      "gridScale": "y",
      "grid": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "domain": false,
      "labels": false,
      "aria": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "gridScale": "x",
      "grid": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "domain": false,
      "labels": false,
      "aria": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    },
    {
      "scale": "x",
      "orient": "bottom",
      "grid": false,
      "title": "Horsepower",
      "labelFlush": true,
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(width/40)"},
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "Miles_per_Gallon",
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 0
    }
  ],
  "legends": [
    {
      "fill": "color",
      "symbolType": "circle",
      "title": "Origin",
      "encode": {"symbols": {"update": {"opacity": {"value": 0.7}}}}
    }
  ]
}