Unable to discretely split up dates

Hi JayWee ,

Not an expert in Vega but I was able to do this using chat GPT:

Preety similar.

You need to  concatenate the axis to get this working:

{
  "data": {
    "name": "dataset"
  },
  "transform": [
    {
      "calculate": "timeFormat(toDate(datum.Date), '%d/%m') + ' - ' + datum.Cat",
      "as": "DateCategory"
    }
  ],
  "mark": {
    "type": "line",
    "point": true,
    "tooltip": true
  },
  "encoding": {
    "x": {
      "field": "DateCategory",
      "type": "ordinal",
      "axis": {
        "title": "Date & Category",
        "labelAngle": -45
      }
    },
    "y": {
      "field": "Sum of Value",
      "type": "quantitative",
      "aggregate": "sum",
      "scale": {
        "zero": false
      }
    }
  }
}

Check the part of the code wher I do the transform of the axis.