Sort the stack segments of barchart - vega-lite

Question

I played with stacked bar charts and wanted to create the Spanish flag with Vega Lite.
I specified the stripes height and color in the data but don't manage to sort the individual stacks:
I set the scale to null, so that the color is taken from the specified field.
I encoded the position of the stripe in the pos attribute, and want to sort the segements by that.
I've also tried to slightly vary the color of the red stripes, but that didn't help.
Spec:
{
"$schema": "https://vega.github.io/schema/vega-lite/v4.json",
"description": "Fun with Flags",
"data": {
"values": [
{"h": 5, "color": "#aa151b", "pos": 6, "country": "spain"},
{"h": 5, "color": "#f1bf00", "pos": 4, "country": "spain"},
{"h": 5, "color": "#aa152b", "pos": 2, "country": "spain"}
]
},
"width": {"step": 300},
"mark": {"type": "bar"},
"encoding": {
"x": {"field": "country", "type": "nominal"},
"y": {"field": "h", "type": "quantitative"},
"color": {
"field": "color",
"scale": null,
"type": "nominal",
"sort": {"field": "pos", "op": "min", "order": "descending"}
}
}
}
Here's a link to the Vega Editor with the Spec.

Answer 1

Instead of sorting the color encoding, I had to specify the order channel, as described in the docs.
This gives me the following spec:
{
"$schema": "https://vega.github.io/schema/vega-lite/v4.json",
"description": "Fun with Flags",
"data": {
"values": [
{"h": 5, "color": "#aa152b", "pos": 6, "country": "spain"},
{"h": 5, "color": "#f1bf00", "pos": 4, "country": "spain"},
{"h": 5, "color": "#aa152b", "pos": 2, "country": "spain"}
]
},
"width": {"step": 300},
"mark": {"type": "bar"},
"encoding": {
"x": {"field": "country", "type": "nominal"},
"y": {"field": "h", "type": "quantitative"},
"color": {
"field": "color",
"scale": null,
"type": "nominal"
},
"order": {
"field": "pos",
"type": "quantitative"
}
}
}
And correct Spanish flag:
Link to Vega Editor