legend2.vl

{
    "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
    "data": {
        "url": "https://vega.github.io/vega-lite/data/cars.json"
    },
    "encoding": {
        "color": {
            "field": "Origin",
            "legend": {
                "orient": "top"
            },
            "type": "nominal"
        },
        "opacity": {
            "field": "Weight_in_lbs",
            "legend": {
                "orient": "top"
            },
            "type": "quantitative"
        },
        "size": {
            "field": "Horsepower",
            "legend": {
                "orient": "top"
            },
            "type": "quantitative"
        },
        "x": {
            "field": "Horsepower",
            "type": "quantitative"
        },
        "y": {
            "field": "Miles_per_Gallon",
            "type": "quantitative"
        }
    },
    "height": 300,
    "mark": "circle",
    "width": 300
}