如何将文本标记添加到 Vega Lite 分组条形图

Posted 2023-02-16

【中文标题】如何将文本标记添加到 Vega Lite 分组条形图

【英文标题】：How to add text mark to a Vega Lite grouped bar chart

【发布时间】：2020-09-18 14:10:14

【问题描述】：

我无法将文本标记图层添加到分组条形图，我尝试编辑 Vega Lite example 以在每个条形图顶部添加总和标签：

https://vega.github.io/editor/#/examples/vega-lite/bar_grouped

但是发生的情况是“层”属性不被接受，或者条被压缩成一个条。如何做到这一点？

【参考方案1】：

当您想向多面图表添加文本标记时，要使用的模式是Facet Operator 中的Layered view。

例如（vega editor）：

  "data": "url": "data/population.json",
  "transform": [
    "filter": "datum.year == 2000",
    "calculate": "datum.sex == 2 ? 'Female' : 'Male'", "as": "gender"
  ],
  "width": "step": 12,
  "facet": "field": "age", "type": "ordinal",
  "spec": 
    "encoding": 
      "y": 
        "aggregate": "sum",
        "field": "people",
        "type": "quantitative",
        "axis": "title": "population", "grid": false
      ,
      "x": "field": "gender", "type": "nominal", "axis": "title": ""
    ,
    "layer": [
      
        "mark": "bar",
        "encoding": 
          "color": 
            "field": "gender",
            "type": "nominal",
            "scale": "range": ["#675193", "#ca8861"]
          
        
      ,
      
        "mark": 
          "type": "text",
          "dx": -5,
          "angle": 90,
          "baseline": "middle",
          "align": "right"
        ,
        "encoding": 
          "text": 
            "aggregate": "sum",
            "field": "people",
            "type": "quantitative",
            "format": ".3s"
          
        
      
    ]
  ,
  "config": 
    "view": "stroke": "transparent",
    "facet": "spacing": 10,
    "axis": "domainWidth": 1
  

【讨论】：

该解决方案有效并给出了预期的结果。使用带有分层视图的规范是我以前没有做过的事情，感谢您的解释！。