HexBin (and default viz. style) fails with less than ~25 points

[SebastianCallh]

Hi! Here is an MRE.

using DataFramesMeta, CairoMakie, PairPlots
df = DataFrame(x = rand(10), y = rand(10))
pairplot(df)

Package versions

[13f3f980] CairoMakie v0.10.4
[1313f7d8] DataFramesMeta v0.14.0
[43a3c2be] PairPlots v1.0.0

Stack trace

ERROR: Can't interpolate in a range where cmin == cmax. This can happen, for example, if a colorrange is set automatically but there's only one unique value present.
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] interpolated_getindex
    @ ~/.julia/packages/Makie/Iqcri/src/colorsampler.jl:36 [inlined]
  [3] #70
    @ ~/.julia/packages/Makie/Iqcri/src/colorsampler.jl:164 [inlined]
  [4] iterate
    @ ./generator.jl:47 [inlined]
  [5] _collect(c::Vector{Float32}, itr::Base.Generator{Vector{Float32}, Makie.var"#70#71"{Vector{ColorTypes.RGBA{Float32}}, ColorTypes.RGBA{Float32}, ColorTypes.RGBA{Float32}, ColorTypes.RGBA{Float32}, Float32, Float32}}, #unused#::Base.EltypeUnknown, isz::Base.HasShape{1})
    @ Base ./array.jl:802
  [6] collect_similar
    @ ./array.jl:711 [inlined]
  [7] map
    @ ./abstractarray.jl:3261 [inlined]
  [8] numbers_to_colors(numbers::Vector{Float32}, colormap::Vector{ColorTypes.RGBA{Float32}}, colorrange::Vec{2, Float32}, lowclip::ColorTypes.RGBA{Float32}, highclip::ColorTypes.RGBA{Float32}, nan_color::ColorTypes.RGBA{Float32})
    @ Makie ~/.julia/packages/Makie/Iqcri/src/colorsampler.jl:156
  [9] numbers_to_colors(numbers::Vector{Float32}, primitive::Scatter{Tuple{Vector{Point{2, Float32}}}})
    @ Makie ~/.julia/packages/Makie/Iqcri/src/colorsampler.jl:147
 [10] to_cairo_color(colors::Vector{Float32}, plot_object::Scatter{Tuple{Vector{Point{2, Float32}}}})
    @ CairoMakie ~/.julia/packages/CairoMakie/0TD4G/src/utils.jl:125

[sefffal]

Hi @SebastianCallh and thanks for the report!
I haven't been able to reproduce this immediately with either rc1 or nightly (but haven't tried rc2 yet).

Is this error repeatable or is it sensitive to the random numbers drawn?

[SebastianCallh]

Hi! No, it is not sensitive to random numbers and I can reproduce it with other data

[sefffal]

Hi @SebastianCallh, I haven't been able to reproduce this issue. Do you have a Manifest.toml file that you could share?

[SebastianCallh]

Curious! Here is a gist with a manifest. https://gist.github.com/SebastianCallh/6c13b831d004b211814fd063dcfd3937
It was produced by running ]add DataFramesMeta, CairoMakie, PairPlots in a new environment.

[SebastianCallh]

Okay I did some more testing and it only seems to happen for small inputs. And the data frame is also a red herring. E.g.

using CairoMakie, PairPlots
df = (;x = randn(1000), y = randn(1000))
pairplot(df)

works but

using CairoMakie, PairPlots
df = (;x = randn(10), y = randn(10))
pairplot(df)

fails

[sefffal]

Ah great catch, thanks!
Looks like an error with the HexBin Makie series specifically:

pairplot((;
	a = randn(10),
	b = randn(10)
)=>(PairPlots.HexBin(),))

fails

Whereas the following work:

pairplot((;
	a = randn(10),
	b = randn(10)
)=>(PairPlots.Scatter(),))
pairplot((;
	a = randn(10),
	b = randn(10)
)=>(PairPlots.Contour(),))
airplot((;
	a = randn(10),
	b = randn(10)
)=>(PairPlots.Hist(),))

[sefffal]

I've filed an issue upstream with Makie.
I'll leave this open to track and possibly add mitigations if they decide not to fix it.

[sefffal]

Closed upstream in Makie. hopefully a release will be tagged soon.