markCondition1.vl

{
    "config": {
        "invalidValues": null
    },
    "mark": "point",
    "data": {
        "url": "https://vega.github.io/vega-lite/data/movies.json"
    },
    "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
    "encoding": {
        "color": {
            "value": "#0099ee",
            "condition": {
                "value": "#ddd",
                "test": {
                    "or": [
                        "datum.IMDB_Rating === null",
                        "datum.Rotten_Tomatoes_Rating === null"
                    ]
                }
            }
        },
        "x": {
            "field": "IMDB_Rating",
            "type": "quantitative"
        },
        "y": {
            "field": "Rotten_Tomatoes_Rating",
            "type": "quantitative"
        }
    }
}