Deneb - Vega Lite Color Gradient Per Category

Hi,

Just wondering if and how it is possible to set the color gradient for category within a visual rather than across the full visual.

The below example shows the gradient based all all categories but is is possible for the color gradient to be applied on each individual category.

{ "data": {"url": "data/cars.json"},

"mark": "rect",

"encoding": { "y": {"field": "Origin", "type": "nominal"},

"x": {"field": "Cylinders", "type": "ordinal"},

"color": {"aggregate": "mean", "field": "Horsepower"} },

"config": { "axis": {"grid": true, "tickBand": "extent"}

} }

Thanks in advance