How i stop Vegalite to rounding of y axis Tick label

Question

I am creating a chart in which i want axis values should be same digit after decimal point as in data , i want this data driven .

I know format in axis but i want to avoid this because it create view like repetative on axis . Is there any way without use of format.

Editor link

I want data driven same upto decimal point as in data because sometime data come upto 2 decimal value and sometime four decimal value

Expected Output

I make this using format but i want this same number of digit as in data (dynamic data driven )

for another use case desire output

Editor Link for Second case senerio

Answer 1

This is non trivial and you still have to use the format expression to get it working. In the example below, I take the first value in your dataset(provided as a string) and use the number of decimal places to specify the format string dynamically. Try changing the first row from 1.000 to 1.0000 for instance.

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "description": "A simple bar chart with embedded data.",
  "background": "white",
  "padding": 5,
  "height": 200,
  "style": "cell",
  "data": [
    {
      "name": "source_0",
      "values": [
        {"a": "A", "b": "1.000"},
        {"a": "B", "b": 2},
        {"a": "C", "b": 3},
        {"a": "D", "b": 4},
        {"a": "E", "b": 5},
        {"a": "F", "b": 6},
        {"a": "G", "b": 7},
        {"a": "H", "b": 8},
        {"a": "I", "b": 9}
      ]
    },
    {
      "name": "data_0",
      "source": "source_0",
      "transform": [
        {
          "type": "stack",
          "groupby": ["a"],
          "field": "b",
          "sort": {"field": [], "order": []},
          "as": ["b_start", "b_end"],
          "offset": "zero"
        },
        {
          "type": "filter",
          "expr": "isValid(datum[\"b\"]) && isFinite(+datum[\"b\"])"
        }
      ]
    }
  ],
  "signals": [
    {"name": "test", "update": "length(split(toString(data('source_0')[0]['b']),'.')[1])"},
    {"name": "x_step", "value": 20},
    {
      "name": "width",
      "update": "bandspace(domain('x').length, 0.1, 0.05) * x_step"
    }
  ],
  "marks": [
    {
      "name": "marks",
      "type": "rect",
      "style": ["bar"],
      "from": {"data": "data_0"},
      "encode": {
        "update": {
          "fill": {"value": "#4c78a8"},
          "ariaRoleDescription": {"value": "bar"},
          "description": {
            "signal": "\"a: \" + (isValid(datum[\"a\"]) ? datum[\"a\"] : \"\"+datum[\"a\"]) + \"; b: \" + (format(datum[\"b\"], \".3f\"))"
          },
          "x": {"scale": "x", "field": "a"},
          "width": {"signal": "max(0.25, bandwidth('x'))"},
          "y": {"scale": "y", "field": "b_end"},
          "y2": {"scale": "y", "field": "b_start"}
        }
      }
    }
  ],
  "scales": [
    {
      "name": "x",
      "type": "band",
      "domain": {"data": "data_0", "field": "a", "sort": true},
      "range": {"step": {"signal": "x_step"}},
      "paddingInner": 0.1,
      "paddingOuter": 0.05
    },
    {
      "name": "y",
      "type": "linear",
      "domain": {"data": "data_0", "fields": ["b_start", "b_end"]},
      "range": [{"signal": "height"}, 0],
      "nice": true,
      "zero": true
    }
  ],
  "axes": [
    {
      "scale": "y",
      "orient": "left",
      "tickRound": false,
      "gridScale": "x",
      "grid": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "domain": false,
      "labels": false,
      "aria": false,
      "maxExtent": 0,
      "minExtent": 0,
      "ticks": false,
      "zindex": 0
    },
    {
      "scale": "x",
      "orient": "bottom",
      "grid": false,
      "title": "a",
      "labelAngle": 90,
      "labelAlign": "left",
      "labelBaseline": "middle",
      "zindex": 0
    },
    {
      "scale": "y",
      "orient": "left",
      "grid": false,
      "title": "b",
      "format": {"signal": "'.'+test+'f'"},
      "tickRound": false,
      "labelOverlap": true,
      "tickCount": {"signal": "ceil(height/40)"},
      "zindex": 0
    }
  ]
}