table1.vl

{
    "mark": "rect",
    "data": {
        "url": "https://vega.github.io/vega-lite/data/cars.json"
    },
    "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
    "encoding": {
        "color": {
            "field": "Horsepower",
            "aggregate": "mean",
            "type": "quantitative"
        },
        "x": {
            "field": "Cylinders",
            "type": "ordinal"
        },
        "y": {
            "field": "Origin",
            "type": "nominal"
        }
    },
    "description": "'Table heatmap' showing engine size/power for three countries."
}