Double box plot

Hi Anonymous, and thanks for such an interesting question! I'm not aware of anything, so I have had a go at building using Deneb with Vega-Lite and the iris dataset, which I hope proves the concept:

While Vega-Lite has a boxplot mark for standard box plots, I needed to calculate the statistics and draw this from primitive marks, so the specification is quite long. I've attached a workbook showing this in action, and I'll list the JSON specification lower down.

Note that because Power BI aggregates measures, you will need to use an index row to ensure that you get all rows in your dataset as intended. In the workbook, this is the Row Number field, and is a sequential field.

If you're not familiar with this concept, I have a blog post here about it, which may help.

Note that this solution is provided as-is, as it took me a few hours to work out, so don't have any time available for further support. If you want to tweak this design, then it's best to have a look at the Vega-Lite documentation to see how the language works. Because Deneb visuals are certified you get many of the advantages you don't get with R and Python visuals, such as full compatibility with publish to web, and PowerPoint & PDF exports.

Cheers,

Daniel

JSON Specification (as per workbook):

{
  "data": {"name": "dataset"},
  "transform": [
    {
      "joinaggregate": [
        {
          "op": "count",
          "field": "Row Number",
          "as": "count"
        },
        {
          "op": "q1",
          "field": "Sepal Length",
          "as": "x_q1"
        },
        {
          "op": "q3",
          "field": "Sepal Length",
          "as": "x_q3"
        },
        {
          "op": "median",
          "field": "Sepal Length",
          "as": "x_median"
        },
        {
          "op": "min",
          "field": "Sepal Length",
          "as": "x_min"
        },
        {
          "op": "max",
          "field": "Sepal Length",
          "as": "x_max"
        },
        {
          "op": "q1",
          "field": "Sepal Width",
          "as": "y_q1"
        },
        {
          "op": "q3",
          "field": "Sepal Width",
          "as": "y_q3"
        },
        {
          "op": "median",
          "field": "Sepal Width",
          "as": "y_median"
        },
        {
          "op": "min",
          "field": "Sepal Width",
          "as": "y_min"
        },
        {
          "op": "max",
          "field": "Sepal Width",
          "as": "y_max"
        }
      ],
      "groupby": ["Species"]
    },
    {
      "calculate": "datum['x_q3'] - datum['x_q1']",
      "as": "x_iqr"
    },
    {
      "calculate": "datum['y_q3'] - datum['y_q1']",
      "as": "y_iqr"
    },
    {
      "calculate": "datum['x_q1'] - 1.5 * datum['x_iqr']",
      "as": "x_lower"
    },
    {
      "calculate": "datum['x_q3'] + 1.5 * datum['x_iqr']",
      "as": "x_upper"
    },
    {
      "calculate": "datum['y_q1'] - 1.5 * datum['y_iqr']",
      "as": "y_lower"
    },
    {
      "calculate": "datum['y_q3'] + 1.5 * datum['y_iqr']",
      "as": "y_upper"
    },
    {
      "calculate": "datum['Sepal Length'] < datum['x_lower'] || datum['Sepal Length'] > datum['x_upper']",
      "as": "x_outlier"
    },
    {
      "calculate": "datum['Sepal Width'] < datum['y_lower'] || datum['Sepal Width'] > datum['y_upper']",
      "as": "y_outlier"
    },
    {
      "calculate": "'x=' + pbiFormat(datum['x_min'], '#0.0') + ', y=' + pbiFormat(datum['y_min'], '#0.0')",
      "as": "tooltip_min"
    },
    {
      "calculate": "'x=' + pbiFormat(datum['x_q1'], '#0.0') + ', y=' + pbiFormat(datum['y_q1'], '#0.0')",
      "as": "tooltip_q1"
    },
    {
      "calculate": "'x=' + pbiFormat(datum['x_median'], '#0.0') + ', y=' + pbiFormat(datum['y_median'], '#0.0')",
      "as": "tooltip_median"
    },
    {
      "calculate": "'x=' + pbiFormat(datum['x_q3'], '#0.0') + ', y=' + pbiFormat(datum['y_q3'], '#0.0')",
      "as": "tooltip_q3"
    },
    {
      "calculate": "'x=' + pbiFormat(datum['x_max'], '#0.0') + ', y=' + pbiFormat(datum['y_max'], '#0.0')",
      "as": "tooltip_max"
    }
  ],
  "layer": [
    {
      "description": "Box plot portion; aggregate our data so that we only get the right number of marks per category.",
      "transform": [
        {
          "aggregate": [],
          "groupby": [
            "Species",
            "count",
            "x_min",
            "x_lower",
            "x_q1",
            "x_median",
            "x_q3",
            "x_upper",
            "x_max",
            "y_min",
            "y_lower",
            "y_q1",
            "y_median",
            "y_q3",
            "y_upper",
            "y_max",
            "tooltip_min",
            "tooltip_q1",
            "tooltip_median",
            "tooltip_q3",
            "tooltip_max"
          ]
        }
      ],
      "layer": [
        {
          "description": "Box (drawn with a rectangle and the x/y quartiles.",
          "mark": {
            "type": "rect",
            "tooltip": true,
            "fillOpacity": 0.5
          },
          "encoding": {
            "x": {"field": "x_q1"},
            "x2": {"field": "x_q3"},
            "y": {"field": "y_q1"},
            "y2": {"field": "y_q3"},
            "stroke": {
              "field": "Species",
              "legend": null
            }
          }
        },
        {
          "description": "x whisker (runs from x lower to x upper and positioned vertically by y median).",
          "mark": {"type": "rule"},
          "encoding": {
            "x": {"field": "x_lower"},
            "x2": {"field": "x_upper"},
            "y": {"field": "y_median"}
          }
        },
        {
          "description": "x lower and upper rules",
          "encoding": {
            "y": {"field": "y_q3"},
            "y2": {"field": "y_q1"}
          },
          "layer": [
            {
              "description": "x lower value",
              "mark": {"type": "rule"},
              "encoding": {
                "x": {
                  "field": "x_lower"
                }
              }
            },
            {
              "description": "x upper value",
              "mark": {"type": "rule"},
              "encoding": {
                "x": {
                  "field": "x_upper"
                }
              }
            }
          ]
        },
        {
          "description": "y whisker (runs from y lower to y upper and positioned vertically by x median).",
          "mark": {"type": "rule"},
          "encoding": {
            "y": {"field": "y_lower"},
            "y2": {"field": "y_upper"},
            "x": {"field": "x_median"}
          }
        },
        {
          "description": "y lower and upper rules",
          "encoding": {
            "x": {"field": "x_q3"},
            "x2": {"field": "x_q1"}
          },
          "layer": [
            {
              "description": "y lower value",
              "mark": {"type": "rule"},
              "encoding": {
                "y": {
                  "field": "y_lower"
                }
              }
            },
            {
              "description": "y upper value",
              "mark": {"type": "rule"},
              "encoding": {
                "y": {
                  "field": "y_upper"
                }
              }
            }
          ]
        }
      ]
    },
    {
      "description": "outlier values.",
      "encoding": {
        "tooltip": [
          {"field": "Species"},
          {"field": "Sepal Width"},
          {"field": "Sepal Length"}
        ]
      },
      "layer": [
        {
          "description": "x outlier values.",
          "transform": [
            {
              "filter": "datum['x_outlier']"
            }
          ],
          "mark": {
            "type": "point",
            "tooltip": true,
            "filled": false
          },
          "encoding": {
            "x": {
              "field": "Sepal Length"
            },
            "y": {"field": "y_median"}
          }
        },
        {
          "description": "y outlier values.",
          "transform": [
            {
              "filter": "datum['y_outlier']"
            }
          ],
          "mark": {
            "type": "point",
            "filled": false,
            "tooltip": true
          },
          "encoding": {
            "y": {
              "field": "Sepal Width"
            },
            "x": {"field": "x_median"}
          }
        }
      ]
    }
  ],
  "encoding": {
    "x": {
      "type": "quantitative",
      "scale": {"zero": false},
      "axis": {"title": "Sepal Length"}
    },
    "y": {
      "type": "quantitative",
      "scale": {"zero": false},
      "axis": {"title": "Sepal Width"}
    },
    "color": {"field": "Species"},
    "tooltip": [
      {"field": "Species"},
      {
        "field": "tooltip_min",
        "title": "Minimum Value"
      },
      {
        "field": "tooltip_q1",
        "title": "Lower Quartile"
      },
      {
        "field": "tooltip_median",
        "title": "Median"
      },
      {
        "field": "tooltip_q3",
        "title": "Upper Quartile"
      },
      {
        "field": "tooltip_max",
        "title": "Maximum Value"
      },
      {
        "field": "count",
        "title": "# Samples"
      }
    ]
  }
}