如何在 Vega-Lite 中创建散点矩阵，其中 row/columns 由值（不是列名）标识

Question

我可以创建一个像 https://vega.github.io/editor/#/examples/vega-lite/interactive_splom 这样的散点矩阵吗？但是 column/rows 是根据分类值而不是列名创建的？

以下示例尝试根据高斯双变量分布中的 3 个值生成散点矩阵。但它只显示一行

{
   "mark": "point",
   "encoding": {
      "x": {
         "field": "value"
      },
      "y": {
         "field": "value"
      },
      "row": {
         "field": "coordinate"
      },
      "column": {
         "field": "coordinate"
      }
   },
   "data": {
      "values": [
         {
            "value": -0.5600273,
            "coordinate": 1
         },
         {
            "value": -0.31220084,
            "coordinate": 2
         },
         {
            "value": -0.37932342,
            "coordinate": 1
         },
         {
            "value": -0.799277,
            "coordinate": 2
         },
         {
            "value": -1.8596855,
            "coordinate": 1
         },
         {
            "value": -3.100046,
            "coordinate": 2
         }
      ]
   }
}

.

Answer 1

从您的数据中不清楚您希望在其他两个面板中出现什么。在绘制坐标 1 与坐标 2 时，哪些数据行会相互关联？

我假设您可以修改您的数据，使其具有第三个字段来指定哪些点放在一起；如果是这样，您可以使用 pivot transform to turn your values into columns, and then use the repeat operator as in the example you linked to (vega editor):

{
  "data": {
    "values": [
      {"value": -0.5600273, "coordinate": 1, "point": 1},
      {"value": -0.31220084, "coordinate": 2, "point": 1},
      {"value": -0.37932342, "coordinate": 1, "point": 2},
      {"value": -0.799277, "coordinate": 2, "point": 2},
      {"value": -1.8596855, "coordinate": 1, "point": 3},
      {"value": -3.100046, "coordinate": 2, "point":3}
    ]
  },
  "transform": [
    {"pivot": "coordinate", "value": "value", "groupby": ["point"]}
  ],
  "repeat": {"row": ["1", "2"], "column": ["1", "2"]},
  "spec": {
    "mark": "point",
    "encoding": {
      "x": {"field": {"repeat": "column"}, "type": "quantitative"},
      "y": {"field": {"repeat": "row"}, "type": "quantitative"}
    }
  }
}

如果您不能将其添加到您的数据集中，而您只想将相邻值视为同一点的一部分，您可以使用一系列转换来指定这一点以构建 "point" 字段和恢复相同的图表（vega editor）：

{
  "data": {
    "values": [
      {"value": -0.5600273, "coordinate": 1},
      {"value": -0.31220084, "coordinate": 2},
      {"value": -0.37932342, "coordinate": 1},
      {"value": -0.799277, "coordinate": 2},
      {"value": -1.8596855, "coordinate": 1},
      {"value": -3.100046, "coordinate": 2}
    ]
  },
  "transform": [
    {"window": [{"op": "row_number", "as": "point"}]},
    {"calculate": "ceil(datum.point / 2)", "as": "point"},
    {"pivot": "coordinate", "value": "value", "groupby": ["point"]}
  ],
  "repeat": {"row": ["1", "2"], "column": ["1", "2"]},
  "spec": {
    "mark": "point",
    "encoding": {
      "x": {"field": {"repeat": "column"}, "type": "quantitative"},
      "y": {"field": {"repeat": "row"}, "type": "quantitative"}
    }
  }
}

如何在 Vega-Lite 中创建散点矩阵，其中 row/columns 由值（不是列名）标识

How to create scatter matrix in Vega-Lite where row/columns are identified by value (not column name)

vega-lite