如何控制Julia双面板图中热力图的宽高比为1？

问题描述 #

想要用Julia绘制双面板图，左侧为热力图，右侧为直方图，初始代码如下（数组X和向量y为已知数据）：

begin
    f = Figure()
    CairoMakie.heatmap(f[1,1], X)
    CairoMakie.hist(f[1,2], y)
    f
end

希望强制左侧热力图宽高比为1，尝试手动创建Axis并设置aspect=1后，代码如下：

begin
    f = Figure()
    ax1 = Axis(f[1,1], aspect = 1)
    ax2 = Axis(f[1,2])
    CairoMakie.heatmap(ax1, X)
    CairoMakie.hist(ax2, y)
    f
end

运行后出现如下错误：

`Makie.convert_arguments` for the plot type MakieCore.Heatmap{Tuple{Makie.MakieLayout.Axis, Matrix{Float64}}} and its conversion trait MakieCore.DiscreteSurface() was unsuccessful.

The signature that could not be converted was:

::Makie.MakieLayout.Axis, ::Matrix{Float32}

Makie needs to convert all plot input arguments to types that can be consumed by the backends (typically Arrays with Float32 elements).

You can define a method for `Makie.convert_arguments` (a type recipe) for these types or their supertypes to make this set of arguments convertible (See http://makie.juliaplots.org/stable/documentation/recipes/index.html).

Alternatively, you can define `Makie.convert_single_argument` for single arguments which have types that are unknown to Makie but which can be converted to known types and fed back to the conversion pipeline.

error(::String)@error.jl:33
var"#convert_arguments#144"(::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, ::typeof(MakieCore.convert_arguments), ::Type{MakieCore.Heatmap{Tuple{Makie.MakieLayout.Axis, Matrix{Float64}}}}, ::Makie.MakieLayout.Axis, ::Vararg{Any})@conversions.jl:17
convert_arguments(::Type{MakieCore.Heatmap{Tuple{Makie.MakieLayout.Axis, Matrix{Float32}}}}, ::Makie.MakieLayout.Axis, ::Matrix{Float32})@conversions.jl:8
convert_arguments_individually(::Type{MakieCore.Heatmap{Tuple{Makie.MakieLayout.Axis, Matrix{Float64}}}}, ::Makie.MakieLayout.Axis, ::Vararg{Any})@conversions.jl:51
var"#convert_arguments#144"(::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, ::typeof(MakieCore.convert_arguments), ::Type{MakieCore.Heatmap{Tuple{Makie.MakieLayout.Axis, Matrix{Float64}}}}, ::Makie.MakieLayout.Axis, ::Vararg{Any})@conversions.jl:14
convert_arguments(::Type{MakieCore.Heatmap{Tuple{Makie.MakieLayout.Axis, Matrix{Float64}}}}, ::Makie.MakieLayout.Axis, ::Matrix{Float64})@conversions.jl:8
var"#plot!#139"(::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}}, ::typeof(MakieCore.plot!), ::Makie.Scene, ::Type{MakieCore.Heatmap}, ::MakieCore.Attributes, ::Makie.MakieLayout.Axis, ::Matrix{Float64})@interfaces.jl:302
plot!(::Makie.Scene, ::Type{MakieCore.Heatmap}, ::MakieCore.Attributes, ::Makie.MakieLayout.Axis, ::Matrix{Float64})@interfaces.jl:288
var"#plot#929"(::NamedTuple{(), Tuple{}}, ::NamedTuple{(), Tuple{}}, ::Base.Pairs{Symbol, Any, Tuple{Symbol, Symbol}, NamedTuple{(:colorrange, :colormap), Tuple{Tuple{Int64, Int64}, Symbol}}}, ::typeof(MakieCore.plot), ::Type{MakieCore.Heatmap}, ::Makie.MakieLayout.Axis, ::Vararg{Any})@figureplotting.jl:28
var"#heatmap#19"(::Base.Pairs{Symbol, Any, Tuple{Symbol, Symbol}, NamedTuple{(:colorrange, :colormap), Tuple{Tuple{Int64, Int64}, Symbol}}}, ::typeof(MakieCore.heatmap), ::Makie.MakieLayout.Axis, ::Vararg{Any})@recipes.jl:33
top-level scope@Local: 6

错误解析 #

这个错误的核心原因是Makie的API调用方式错误：

• CairoMakie.heatmap() 函数默认用于创建新的绘图场景或轴并绘制热力图，第一个参数应为布局位置（如f[1,1]），而非已有的Axis对象。
• 若要在已创建好的Axis上绘制，必须使用带感叹号的突变版本函数heatmap!()，直方图对应hist!()。直接将Axis传给不带感叹号的heatmap，Makie无法识别该参数组合，导致参数转换失败。

解决方案 #

提供两种可行的实现方式：

方式1：手动创建Axis并使用突变绘图函数 #

修正API调用，用heatmap!和hist!在已创建的Axis上绘制：

begin
    f = Figure()
    ax1 = Axis(f[1,1], aspect = 1)  # 设置宽高比为1
    ax2 = Axis(f[1,2])
    CairoMakie.heatmap!(ax1, X)     # 用!版本在已有Axis上绘制
    CairoMakie.hist!(ax2, y)        # 直方图同理
    f
end

方式2：直接在布局位置设置轴属性（更简洁） #

无需手动创建Axis，直接通过axis关键字参数在heatmap函数中设置宽高比：

begin
    f = Figure()
    CairoMakie.heatmap(f[1,1], X, axis=(aspect=1,))  # 直接指定轴的宽高比
    CairoMakie.hist(f[1,2], y)
    f
end

两种方式都能实现左侧热力图宽高比强制为1的需求，方式2代码更简洁，适合快速实现。

内容的提问来源于stack exchange，提问作者seeker_after_truth