How to remove an item from the legend in Vega-Lite

Question

Is it possible to remove an item from the legend? The number of categories in the legend is dynamic, so I can't use manually-entered list of entries for the legend.

If I use

"labelExpr": "datum.label == '_Support' ? null : datum.label",

it will remove the label, but keep its symbol.

Before suppresion

After suppression

Answer 1

I have hidden a symbol for x here:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [
      {"category": "A", "group": "x", "value": 0.1},
      {"category": "A", "group": "y", "value": 0.6},
      {"category": "A", "group": "z", "value": 0.9},
      {"category": "B", "group": "x", "value": 0.7},
      {"category": "B", "group": "y", "value": 0.2},
      {"category": "B", "group": "z", "value": 1.1},
      {"category": "C", "group": "x", "value": 0.6},
      {"category": "C", "group": "y", "value": 0.1},
      {"category": "C", "group": "z", "value": 0.2}
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {"field": "category"},
    "y": {"field": "value", "type": "quantitative"},
    "xOffset": {"field": "group"},
    "color": {
      "field": "group",
      "legend": {"symbolSize": {"expr": "datum.label=='x'?0:100"}}
    }
  }
}