VL Test case

vl_comapare_sample.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
  "description": "Drag the sliders to highlight points.",
  "data": {"url": "data/cars.json"},
  "selection": {"CylYr": {"type": "multi"}},
  "mark": "circle",
  "encoding": {
    "x": {"field": "Horsepower", "type": "quantitative"},
    "y": {"field": "Miles_per_Gallon", "type": "quantitative"},
    "color": {
      "condition": {
        "test": {
          "and": [
            {
              "field": "Horsepower",
              "gte": {
                "selection": "CylYr",
                "aggregate": "mean",
                "field": "Horsepower"
              }
            },
            {
              "field": "Miles_per_Gallon",
              "gte": {
                "selection": "CylYr",
                "aggregate": "mean",
                "field": "Miles_per_Gallon"
              }
            }
          ]
        },
        "field": "Origin",
        "type": "nominal"
      },
      "value": "grey"
    }
  }
}