如何控制Vega-lite堆叠条形图中的组顺序

Question

给出一个堆叠的条形图，例如本示例：https://vega.github.io/editor/?#/examples/vega-lite/stacked_bar_weather

我想控制聚合中项目的顺序，例如，“雾”位于底部，“太阳”位于其下，等等。

原因是我有一种类型比其他类型大得多。我希望它显示在底部，然后控制域以“切断”该部分的大部分内容。

谢谢

Answer 1

您可以通过order编码来控制堆栈顺序：请参见https://vega.github.io/vega-lite/docs/stack.html#sorting-stack-order

不幸的是，这仅允许按字段值排序，而不是按此处想要的显式顺序排序。解决方法是使用calculate transform将您的显式顺序转换为字段（view in editor）：

{
  "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
  "data": {"url": "data/seattle-weather.csv"},
  "transform": [
    {
      "calculate": "indexof(['sun', 'fog', 'drizzle', 'rain', 'snow'], datum.weather)",
      "as": "order"
    }
  ],
  "mark": "bar",
  "encoding": {
    "x": {
      "timeUnit": "month",
      "field": "date",
      "type": "ordinal",
      "axis": {"title": "Month of the year"}
    },
    "y": {"aggregate": "count", "type": "quantitative"},
    "color": {
      "field": "weather",
      "type": "nominal",
      "scale": {
        "domain": ["sun", "fog", "drizzle", "rain", "snow"],
        "range": ["#e7ba52", "#c7c7c7", "#aec7e8", "#1f77b4", "#9467bd"]
      },
      "legend": {"title": "Weather type"}
    },
    "order": {"field": "order", "type": "ordinal"}
  }
}