hexbin fails when there are less than ~25 points

[sefffal]

The hexbin plot command fails when the input size is small.

For example, the following command works as expected:

hexbin(randn(100), randn(100))

But this does not (see error message below):

hexbin(randn(10), randn(10))

It seems to me that hexbins should be well defined with arbitrarily few points.

X-ref: sefffal/PairPlots.jl#16

Tested with latest stable CairoMakie and Julia 1.9-rc2.

Error message:

Failed to show value:

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.

error(::String)@error.jl:35
interpolated_getindex@colorsampler.jl:36[inlined]
#70@colorsampler.jl:164[inlined]
iterate@generator.jl:47[inlined]
_collect(::Vector{Float32}, ::Base.Generator{Vector{Float32}, Makie.var"#70#71"{Vector{ColorTypes.RGBA{Float32}}, ColorTypes.RGBA{Float32}, ColorTypes.RGBA{Float32}, ColorTypes.RGBA{Float32}, Float32, Float32}}, ::Base.EltypeUnknown, ::Base.HasShape{1})@array.jl:802
collect_similar@array.jl:711[inlined]
map@abstractarray.jl:3261[inlined]
numbers_to_colors(::Vector{Float32}, ::Vector{ColorTypes.RGBA{Float32}}, ::GeometryBasics.Vec{2, Float32}, ::ColorTypes.RGBA{Float32}, ::ColorTypes.RGBA{Float32}, ::ColorTypes.RGBA{Float32})@colorsampler.jl:156
numbers_to_colors(::Vector{Float32}, ::MakieCore.Scatter{Tuple{Vector{GeometryBasics.Point{2, Float32}}}})@colorsampler.jl:147
to_cairo_color(::Vector{Float32}, ::MakieCore.Scatter{Tuple{Vector{GeometryBasics.Point{2, Float32}}}})@utils.jl:125
draw_atomic(::Makie.Scene, ::CairoMakie.Screen{CairoMakie.IMAGE}, ::MakieCore.Scatter)@primitives.jl:222
draw_plot(::Makie.Scene, ::CairoMakie.Screen{CairoMakie.IMAGE}, ::MakieCore.Scatter{Tuple{Vector{GeometryBasics.Point{2, Float32}}}})@infrastructure.jl:108
draw_plot(::Makie.Scene, ::CairoMakie.Screen{CairoMakie.IMAGE}, ::MakieCore.Combined{Makie.hexbin, Tuple{Vector{GeometryBasics.Point{2, Float32}}}})@infrastructure.jl:113
cairo_draw(::CairoMakie.Screen{CairoMakie.IMAGE}, ::Makie.Scene)@infrastructure.jl:49
backend_show(::CairoMakie.Screen{CairoMakie.IMAGE}, ::IOContext{IOBuffer}, ::MIME{Symbol("image/png")}, ::Makie.Scene)@display.jl:111
show(::IOContext{IOBuffer}, ::MIME{Symbol("image/png")}, ::Makie.FigureAxisPlot)@display.jl:193

[asinghvi17]

I think this is because only one cell is being generated. We could put in some code to handle this.

[sefffal]

Thinking more about this, I'm curious how only one cell could be generated for 10 random points.

Maybe there is also a bug in the bin-sizing algorithm?