drilldown_timeunit_bar

spec.json

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"url": "data/seattle-weather.csv"},
  "width": 600,
  "layer": [
    {
      "params": [
        {"name": "brush", "select": {"type": "interval", "encodings": ["x"]}}
      ],
      "mark": "bar",
      "encoding": {
        "x": {"timeUnit": "month", "field": "date", "type": "temporal"},
        "y": {
          "aggregate": "mean",
          "field": "precipitation",
          "type": "quantitative"
        },
        "opacity": {"condition": {"param": "brush", "value": 1}, "value": 0.7}
      }
    }
  ]
}