filter2.vl

{
    "transform": [
        {
            "filter": {
                "field": "IMDB_Rating",
                "valid": true
            }
        },
        {
            "filter": {
                "field": "Rotten_Tomatoes_Rating",
                "valid": true
            }
        }
    ],
    "config": {
        "mark": {
            "invalid": "filter"
        }
    },
    "mark": "point",
    "data": {
        "url": "https://vega.github.io/vega-lite/data/movies.json"
    },
    "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
    "encoding": {
        "color": {
            "value": "rgb(76,120,168)",
            "condition": {
                "value": "#ddd",
                "test": "datum.IMDB_Rating === null || datum.Rotten_Tomatoes_Rating === null"
            }
        },
        "x": {
            "field": "IMDB_Rating",
            "type": "quantitative"
        },
        "y": {
            "field": "Rotten_Tomatoes_Rating",
            "type": "quantitative"
        }
    }
}