Vega：在数据中添加丢失的信息

Question

在kibana中，在Vega-lite可视化中，我想随时间创建应用程序（AAAA）的过渡状态图。 （时间轴）
状态具有固定值（init，start，running ...）

在x轴上的时间戳记，
在州一级，
用于跟踪状态级别的矩形或条形。

| ====
| ======
| ===========
______________________________
 t0 t1 t2 ....

我的数据来自ElasticSearch中的查询，并具有以下格式。

timestamp  app  state
  t0    AAAA  Init
  t1    AAAA  start
  t2    AAAA  Running
  t3    AAAA  stopped

在vega中，我想用条形或矩形表示状态， 例如：Init状态将由从t0开始到t1结束的矩形表示。但是我没有这个信息！ t1在下一条数据行中

是否有可能通过利用下一行来计算该值。 数据将是这样。

timestamp  app  state    ends 
  t0    AAAA  Init         t1
  t1    AAAA  start        t2 
  t2    AAAA  Running      t3
  t3    AAAA  stopped      t4 

任何帮助都将受到欢迎。

Answer 1

您可以使用lead操作通过窗口变换来找到下一个值。例如：

{
  "data": {
    "values": [
      {"timestamp": 0, "app": "A", "state": "init"},
      {"timestamp": 10, "app": "A", "state": "start"},
      {"timestamp": 25, "app": "A", "state": "run"},
      {"timestamp": 30, "app": "A", "state": "stop"},
      {"timestamp": 40, "app": "B", "state": "init"},
      {"timestamp": 55, "app": "B", "state": "start"},
      {"timestamp": 75, "app": "B", "state": "run"},
      {"timestamp": 85, "app": "B", "state": "stop"},
      {"timestamp": 90, "app": null, "state": "init"}
    ]
  },
  "transform": [
    {"window": [{"op": "lead", "field": "timestamp", "as": "t_stop"}]},
    {"filter": "datum.app != null"}
  ],
  "encoding": {
    "color": {"type": "nominal", "field": "app"},
    "x": {"type": "quantitative", "field": "timestamp"},
    "x2": {"type": "quantitative", "field": "t_stop"},
    "y": {
      "type": "nominal",
      "field": "state",
      "sort": {"op": "sum", "field": "timestamp", "order": "ascending"}
    }
  },
  "mark": "bar",
  "$schema": "https://vega.github.io/schema/vega-lite/v2.6.0.json"
}