tickMinStep ignored for small domain values

[parente]

Please:

• Describe how to reproduce the bug.

tickMinStep=1 seems to be ignored in v5.8.0 of vega-lite when for domain values less than 5. Ticks appear with floating point values instead of integers only (e.g., as they were in this prior issue example: #7034)

• Check for duplicate issues. Please file separate requests as separate issues.

I could not find an open bug searching for tickMinStep in the GitHub issues for this repository.

• Use the latest versions of Vega and Vega-Lite.

I tested using vega-lite 5.8.0.

• Provide an minimal, reproducible example spec in JSON, wrapped by triple backticks like this:

Example with v4 schema, repurposed from #7034 (Open the chart in the Vega Editor)

{
  "$schema": "https://vega.github.io/schema/vega-lite/v4.json",
  "description": "A simple bar chart with embedded data.",
  "data": {
    "values": [
      {"a": "A", "b": 2}, {"a": "B", "b": 1}, {"a": "C", "b": 1},
      {"a": "D", "b": 1}, {"a": "E", "b": 2}, {"a": "F", "b": 2},
      {"a": "G", "b": 3}, {"a": "H", "b": 3}, {"a": "I", "b": 1}
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {"field": "a", "type": "nominal", "axis": {"labelAngle": 0}},
    "y": {"field": "b", "type": "quantitative", "axis": {"tickMinStep": 1}}
  }
}

Example using v5 schema (Open the chart in the Vega Editor)

{
  "config": {"view": {"continuousWidth": 300, "continuousHeight": 300}},
  "data": {"name": "data-4a0cb25b0716723cd309daa74d88bb73"},
  "mark": {"type": "point"},
  "encoding": {
    "x": {"axis": {"tickMinStep": 1}, "field": "x", "type": "quantitative"},
    "y": {"field": "y", "type": "quantitative"}
  },
  "$schema": "https://vega.github.io/schema/vega-lite/v5.8.0.json",
  "datasets": {
    "data-4a0cb25b0716723cd309daa74d88bb73": [
      {"x": 0, "y": 0},
      {"x": 1, "y": 1},
      {"x": 2, "y": 2},
      {"x": 3, "y": 3},
      {"x": 4, "y": 4}
    ]
  }
}

• If applicable, include error messages and screenshots, GIF videos (e.g. using https://www.cockos.com/licecap/), or working examples (e.g. by clicking share in the Vega-Editor or https://bit.ly/vega-lite-blocks)

[jonmmease]

It looks to me, as of Vega-Lite 5.14.1, that tickMinStep is always ignored.

Here's an example of a histogram with an attempt to limit x-tick spacing to be no smaller than 2 domain units. But the result still includes tick spacing of 1 unit.

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"url": "data/movies.json"},
  "mark": "bar",
  "encoding": {
    "x": {
      "bin": true,
      "field": "IMDB Rating",
      "axis": {
        "grid": true,
        "tickMinStep": 2
      }
    },
    "y": {"aggregate": "count"}
  }
}

Open the Chart in the Vega Editor

When changing the value of tickMinStep, the generated Vega spec doesn't change at all.

ping @kanitw as it looks like you did some work with tickMinStep earlier this year in #8872.

[jonmmease]

Friendly ping @kanitw. Not certain this was related to your changes, but wondering if you could take a quick look