如何在含repeat配置的Vega-Lite图例上启用鼠标点击事件？

当你用repeat.layer生成多图层时，直接在子spec中定义绑定图例的params会导致每个图层都创建同名信号，触发重复信号错误。解决思路是把交互参数移到顶层配置，统一管理信号，避免重复定义。

以下是修正后的完整配置：

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"url": "data/movies.json"},
  "params": [
    {
      "name": "toggleSeries",
      "select": {"type": "point", "fields": ["series"], "toggle": true},
      "value": [{"series": "US Gross"}, {"series": "Worldwide Gross"}]
    }
  ],
  "repeat": {"layer": ["US Gross", "Worldwide Gross"]},
  "spec": {
    "mark": "line",
    "encoding": {
      "x": {"bin": true, "field": "IMDB Rating", "type": "quantitative"},
      "y": {
        "aggregate": "mean",
        "field": {"repeat": "layer"},
        "type": "quantitative",
        "title": "Mean of US and Worldwide Gross"
      },
      "color": {
        "datum": {"repeat": "layer"},
        "type": "nominal",
        "legend": {"title": "Gross Type"}
      },
      "opacity": {
        "condition": {"param": "toggleSeries", "test": "indexof(datum.series, repeat('layer')) !== -1", "value": 1},
        "value": 0.1
      }
    }
  },
  "config": {
    "legend": {"bind": "toggle"}
  }
}

关键改动说明：

• 顶层定义toggleSeries参数，统一管理系列的选中状态，避免repeat重复生成信号
• 用opacity编码的condition判断当前系列是否在选中参数中，控制显示/隐藏
• 顶层config中设置legend.bind: toggle，让图例直接绑定顶层参数，实现点击图例切换系列可见性

内容的提问来源于stack exchange，提问作者Raghav Khare