Vega-Lite order Channel

Use the order encoding channel to control how Vega-Lite draws marks. It is most useful for:

• stacked marks (bar, area, arc)
• path marks (line, trail, area)

{
  "encoding": {
    "order": {"field": "sort_key", "type": "quantitative"}
  }
}

order vs sort

These two are related but solve different problems.

If your axis looks right but stacks are still in the wrong sequence, you usually need order, not sort.

Example 1: Control Stacking Sequence

The left chart uses default stack order. The right chart uses encoding.order with tier_order.

Vega-Lite spec used in the right chart:

{
  "mark": "bar",
  "encoding": {
    "x": {"field": "quarter", "type": "nominal"},
    "y": {"field": "amount", "type": "quantitative"},
    "color": {"field": "tier", "type": "nominal"},
    "order": {"field": "tier_order", "type": "quantitative"}
  }
}

Example 2: Order Points in a Line Path

For path marks, order controls the connection sequence of points.

{
  "mark": "line",
  "encoding": {
    "x": {"field": "month", "type": "ordinal", "sort": ["Jan", "Feb", "Mar", "Apr"]},
    "y": {"field": "value", "type": "quantitative"},
    "detail": {"field": "city", "type": "nominal"},
    "order": {"field": "month_index", "type": "quantitative"}
  }
}

In this example:

• x.sort controls axis label order.
• order controls the point connection sequence for each line.

FAQ

When should I use order?

Use it when the sequence of drawing matters, especially for stacked marks and line/trail paths.

Why doesn't sort fix my stack sequence?

sort affects domain ordering (axis/legend). Stack drawing sequence is controlled by encoding.order.

Can I use a calculated field for order?

Yes. A common pattern is to create a numeric rank with calculate, then map that field to encoding.order.