Vega Lite - scatter plot

Hi AdamMG,

If you just want to draw a line across the width/height of the visible view, you can do something like this, where you create a layer with a simple, empty dataset (like the fixed line example) :

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"url": "data/cars.json"},
  "layer": [
    {
      "data": {"values": [{}]},
      "mark": "rule",
      "encoding": {
        "x": {"value": 0},
        "x2": {"value": "width"},
        "y": {"value": "height"},
        "y2": {"value": 0}
      }
    },
    {
      "mark": "point",
      "encoding": {
        "x": {"field": "Horsepower"},
        "y": {"field": "Miles_per_Gallon"}
      }
    }
  ],
  "encoding": {"x": {"type": "quantitative"}, "y": {"type": "quantitative"}}
}

Link to sample specification

You could also use the expression language to interrogate the assigned scale domains, e.g.:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"url": "data/cars.json"},
  "layer": [
    {
      "data": {"values": [{}]},
      "mark": "rule",
      "encoding": {
        "x": {"datum": {"expr": "domain('x')[0]"}},
        "x2": {"datum": {"expr": "domain('x')[1]"}},
        "y": {"datum": {"expr": "domain('y')[0]"}},
        "y2": {"datum": {"expr": "domain('y')[1]"}}
      }
    },
    {
      "mark": "point",
      "encoding": {
        "x": {"field": "Horsepower"},
        "y": {"field": "Miles_per_Gallon"}
      }
    }
  ],
  "encoding": {"x": {"type": "quantitative"}, "y": {"type": "quantitative"}}
}

Link to sample specification

If you want to do something fancier with the range of data for each encoding channel, this may be possible but would require a sample of your dataset to ensure that I could come up with an optimal approach. If you're not able to share, you might be able to consider an aggregate transform, to find the min/max of each series and plot based on those, or possibly a regression transform may be an option.

Hopefully, some of this may help you come up with more ideas. And thanks very much for trying Deneb!

Regards,

Daniel