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jonespossibly's avatar
jonespossibly
Icon for Advocate I rankAdvocate I
4 years ago

Deneb Vega-lite trend line based on aggregated mark

I've got a line chart in which i have a line that is aggregated by sum. I have a trend line based on regression which works fine for the none-aggregated data, but i would like it to show a trend line...
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  • jonespossibly's avatar
    jonespossibly
    Icon for Advocate I rankAdvocate I
    4 years ago

    ok, so I've set up test data and specification below - how do i base the trend line on the total?

    {
  "data": {"values":[
 {
   "Weekly Avg": "2",
   "Type": "a",
   "WC": "2022-01-01 00:00:00"
 },
 {
   "Weekly Avg": "4",
   "Type": "b",
   "WC": "2022-01-01 00:00:00"
 },
 {
   "Weekly Avg": "23",
   "Type": "c",
   "WC": "2022-01-01 00:00:00"
 },
 {
   "Weekly Avg": "28",
   "Type": "a",
   "WC": "2022-01-08 00:00:00"
 },
 {
   "Weekly Avg": "22",
   "Type": "b",
   "WC": "2022-01-08 00:00:00"
 },
 {
   "Weekly Avg": "25",
   "Type": "c",
   "WC": "2022-01-08 00:00:00"
 },
 {
   "Weekly Avg": "42",
   "Type": "a",
   "WC": "2022-01-15 00:00:00"
 },
 {
   "Weekly Avg": "21",
   "Type": "b",
   "WC": "2022-01-15 00:00:00"
 },
 {
   "Weekly Avg": "17",
   "Type": "c",
   "WC": "2022-01-15 00:00:00"
 },
 {
   "Weekly Avg": "42",
   "Type": "a",
   "WC": "2022-01-22 00:00:00"
 },
 {
   "Weekly Avg": "11",
   "Type": "b",
   "WC": "2022-01-22 00:00:00"
 },
 {
   "Weekly Avg": "27",
   "Type": "c",
   "WC": "2022-01-22 00:00:00"
 },
 {
   "Weekly Avg": "22",
   "Type": "a",
   "WC": "2022-01-29 00:00:00"
 },
 {
   "Weekly Avg": "11",
   "Type": "b",
   "WC": "2022-01-29 00:00:00"
 },
 {
   "Weekly Avg": "13",
   "Type": "c",
   "WC": "2022-01-29 00:00:00"
 }
]},
  "layer": [
    {
      "mark": {"type": "line"},
      "encoding": {
        "y": {"field": "Weekly Avg"},
        "color": {
          "field": "Type",
          "scale": {
            "range": [
              "#4795CA",
              "#F9B96A",
              "#779E41",
              "#F54f0F",
              "#cfcfcf"
            ]
          }
        }
      }
    },
    {
      "mark": {"type": "line"},
      "encoding": {
        "y": {
          "field": "Weekly Avg",
          "aggregate": "sum"
        },
        "color": {"datum": "Total"}
      }
    },
    {
      "mark": {
        "type": "line",
        "strokeDash": [5, 5]
      },
      "transform": [
        {
          "regression": "Weekly Avg",
          "on": "WC",
          "groupBy": "WC"
        }
      ],
      "encoding": {
        "y": {
          "field": "Weekly Avg"
        },
        "color": {"datum": "Trend"}
      }
    }
  ],
  "encoding": {
    "x": {
      "field": "WC",
      "timeUnit": "monthdateyear",
      "type": "ordinal",
      "axis": {"format": "%d/%m/%Y"}
    },
    "y": {
      "type": "quantitative",
      "axis": {"format": "~s"}
    }
  }
}