bar9.vl

{
    "mark": "bar",
    "data": {
        "values": [
            {
                "color": "red",
                "b": 28
            },
            {
                "color": "green",
                "b": 55
            },
            {
                "color": "blue",
                "b": 43
            }
        ]
    },
    "$schema": "https://vega.github.io/schema/vega-lite/v3.json",
    "encoding": {
        "color": {
            "field": "color",
            "scale": null,
            "type": "nominal"
        },
        "x": {
            "field": "color",
            "type": "nominal"
        },
        "y": {
            "field": "b",
            "type": "quantitative"
        }
    },
    "description": "A bar chart that directly encodes color names in the data."
}