Empty categories are not shown if proceed existing categories

[h-spiess]

Bug description

categories can be passed to scales to show empty categories too. This usually works. However, if the empty categories come before the existing categories in the passed list it does not work.

Steps to reproduce

using AlgebraOfGraphics
using CairoMakie

spec = data((; group = ["B", "C", "D"], value = [1, 3, 4])) *
    mapping(:group, :value) * visual(BarPlot)

fig = Figure()

draw!(fig[1, 1], spec, scales(
    X = (; categories = ["A", "B", "C", "D"])
))
fig

Images

Version info

Julia Version 1.11.3
Commit d63adeda50d (2025-01-21 19:42 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: macOS (arm64-apple-darwin24.0.0)
  CPU: 10 × Apple M1 Max
  WORD_SIZE: 64
  LLVM: libLLVM-16.0.6 (ORCJIT, apple-m1)
Threads: 8 default, 0 interactive, 4 GC (on 8 virtual cores)
Environment:
  JULIA_REVISE_WORKER_ONLY = 1

Status `~/Documents/PhD/NI/Lehre_PPR/Exam_Summary/Project.toml`
  [cbdf2221] AlgebraOfGraphics v0.10.0
  [336ed68f] CSV v0.10.15
  [13f3f980] CairoMakie v0.13.2
  [a93c6f00] DataFrames v1.7.0
⌃ [7f904dfe] PlutoUI v0.7.61
  [37e2e46d] LinearAlgebra v1.11.0
Info Packages marked with ⌃ have new versions available and may be upgradable.```

[jkrumbiegel]

The problem here is that Makie sets the limits more tightly than you want, not that the categories themselves don't exist in the ticks. I've been wondering if AlgebraOfGraphics should enforce a minimal range of limits for categorical scales for that reason. Maybe this could be done by adding an invisible plot there.

[h-spiess]

Thanks for the fast answer. Unfortunately. I'm not that familiar with AlgebraOfGraphics or Makie yet. What would the easy fix look like?

[h-spiess]

Okay, I just adjusted the lower limit of CairoMakie.xlims! to 0. However, I think this should happen automatically when categories are passed. Would be a great addition for the future.