Vega boxplot using mtcars

gistfile1.txt

{
  "name": "boxplot",
  "height": 200,
  "padding": "auto",
  "width": 600,
  "signals": [
    {
      "name": "boxSize",
      "init": 40
    }
  ],
  "axes": [
    {
      "type": "x",
      "scale": "x"
    },
    {
      "offset": 5,
      "properties": {
        "axis": {
          "stroke": {
            "value": "transparent"
          }
        }
      },
      "type": "y",
      "scale": "y",
      "tickSize": 0
    }
  ],
  "scales": [
    {
      "name": "y",
      "points": true,
      "padding": 1.5,
      "range": "height",
      "domain": {
        "data": "table",
        "field": "x"
      },
      "type": "ordinal",
      "round": true
    },
    {
      "name": "x",
      "nice": true,
      "range": "width",
      "domain": {
        "data": "table",
        "field": [
          "y"
        ]
      },
      "type": "linear",
      "round": true
    }
  ],
  "data": [
    {
      "name": "table",
      "values": [
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 21
        },
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 21
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 22.8
        },
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 21.4
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 18.7
        },
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 18.1
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 14.3
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 24.4
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 22.8
        },
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 19.2
        },
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 17.8
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 16.4
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 17.3
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 15.2
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 10.4
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 10.4
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 14.7
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 32.4
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 30.4
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 33.9
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 21.5
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 15.5
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 15.2
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 13.3
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 19.2
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 27.3
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 26
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 30.4
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 15.8
        },
        {
          "x": 6,
          "y2": 0,
          "group": 1,
          "y": 19.7
        },
        {
          "x": 8,
          "y2": 0,
          "group": 1,
          "y": 15
        },
        {
          "x": 4,
          "y2": 0,
          "group": 1,
          "y": 21.4
        }
      ]
    },
    {
      "name": "stats",
      "source": "table",
      "transform": [
        {
          "type": "aggregate",
          "groupby": [
            "x"
          ],
          "summarize": {
            "y": ["min","max", "median", "q1", "q3", "valid"]
          }
        }
      ]
    },
    {
      "name": "iqrcalcs",
      "source": "stats",
      "transform": [{"type": "formula", "field": "lower", "expr": "max(datum.min_y,datum.q1_y-1.5*(datum.q3_y-datum.q1_y))"},
                    {"type": "formula", "field": "upper", "expr": "min(datum.max_y,datum.q3_y+1.5*(datum.q3_y-datum.q1_y))"}]
    }
  ],
  "marks": [
    {
      "properties": {
        "enter": {
          "height": {
            "value": 1
          },
          "x2": {
            "field": "upper",
            "scale": "x"
          },
          "x": {
            "field": "lower",
            "scale": "x"
          },
          "yc": {
            "field": "x",
            "scale": "y"
          },
          "fill": {
            "value": "#888"
          }
        }
      },
      "from": {
        "data": "iqrcalcs"
      },
      "type": "rect"
    },
    {
      "type": "rect",
      "from": {"data": "iqrcalcs"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "q1_y"},
          "x2": {"scale": "x", "field": "q3_y"},
          "yc": {"scale": "y", "field": "x"},
          "height": {"signal": "boxSize"},
          "fill": {"value": "green"},
          "stroke": {"value": "#888"}
        }
      }
    },
     {
      "type": "rect",
      "from": {"data": "iqrcalcs"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "median_y"},
          "width": {"value": 2},
          "yc": {"scale": "y", "field": "x"},
          "height": {"signal": "boxSize"},
          "fill": {"value": "#000"}
        }
      }
    },
    {
      "type": "rect",
      "from": {"data": "iqrcalcs"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "lower"},
          "width": {"value": 1},
          "yc": {"scale": "y", "field": "x"},
          "height": {"signal": "boxSize", "mult": 0.5},
          "fill": {"value": "#000"}
        }
      }
    },
    {
      "type": "rect",
      "from": {"data": "iqrcalcs"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "upper"},
          "width": {"value": 1},
          "yc": {"scale": "y", "field": "x"},
          "height": {"signal": "boxSize", "mult": 0.5},
          "fill": {"value": "#000"}
        }
      }
    },
    {
      "type": "symbol",
      "from": {"data": "stats"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "min_y"},
          "yc": {"scale": "y", "field": "x"},
          "size": {"value": 20},
          "stroke": {"value": "#000"},
          "fill": {"value": "#fff"}
          
        }
      }
    },
     {
      "type": "symbol",
      "from": {"data": "stats"},
      "properties": {
        "enter": {
          "x": {"scale": "x", "field": "max_y"},
          "yc": {"scale": "y", "field": "x"},
          "size": {"value": 20},
          "stroke": {"value": "#000"},
          "fill": {"value": "#fff"}
          
        }
      }
    }
  ]
}