Deneb Vega-lite trend line based on aggregated mark

[jonespossibly]

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 based on the points given by the aggregate.

here is my vega-lite specification - can someone help me out?:

  "data": {"name": "dataset"},
  "layer": [
    {
      "mark": {"type": "line"},
      "encoding": {
        "y": {
          "field": "Weekly Avg"
        },
        "color": {
          "field": "Loan 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": "W / C",
          "groupBy": "W / C"
        
        }
      ],
      "encoding": {
        "y": {
          "field": "Weekly Avg"
        },
        "color": {"datum": "Trend"}
      }
    }
  ],
  "encoding": {
    "x": {
      "field": "W / C",
      "timeUnit": "monthdateyear",
      "type": "ordinal",
      "axis": {"format": "%d/%m/%Y"}
    },
    "y": {
      "type": "quantitative",
      "axis": {"format": "~s"}
    }
  }
}

 #deneb #vega-lite

[mahoneypat]

This would be easier to help do with data. Please see this video on how to add your data into the json (or you can just provide link to your sample data).

(2) Getting Help With the Deneb Visual in Power BI - YouTube

Pat

[jonespossibly]

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"}
    }
  }
}