A bar chart encoding color names in the data

{
  "$schema": "https://vega.github.io/schema/vega-lite/v2.json",
  "description": "A bar chart that directly encodes color names in the data.",
  "data": {
    "values": [
      {
        "color": "red",
        "b": 28
      },
      {
        "color": "green",
        "b": 55
      },
      {
        "color": "blue",
        "b": 43
      }
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {
      "field": "color",
      "type": "nominal"
    },
    "y": {
      "field": "b",
      "type": "quantitative"
    },
    "color": {
      "field": "color",
      "type": "nominal",
      "scale": null
    }
  }
}