Redirect a plot type in Makie while keeping color consistent

jling · March 22, 2024, 2:32pm

I have a histogram type that I’d like to customize its plotting for a few type of plots: Scatter, BarPlot, Hist, StepHist etc.

For some of them, this is very straight forward:

julia> using CairoMakie

julia> struct MyHist
           bincounts
           binedges
       end

julia> h = MyHist([1, 10, 100], 0:3)

julia> Makie.convert_arguments(P::Type{<:Stairs}, h::MyHist) = convert_arguments(P, h.binedges, [0; h.bincounts])

julia> stairs(h)

However, for plot type such as StepHist, I failed to properly “override” the plot, what I tried is to define:

function Makie.plot!(input::StepHist{<:Tuple{<:MyHist}})
    h = input[1][]
    Makie.stairs!(input, h)
    input
end

this works in the naive case, which would produce exactly the same plot as above:

julia> h = MyHist([1, 10, 100], 0:3)

julia> stephist(h)

However, it fails when we use it together with other stuff:

stephist(h; color=:red)

So initially I tried to fix this by changing the definition of plot!() to:

function Makie.plot!(input::StepHist{<:Tuple{<:MyHist}})
    h = input[1][]
    C = input[:color][]
    Makie.stairs!(input, h; color=C)
    input
end

now this works:

stephist(h; color=:red)

but there are edge cases like:

julia> begin
           stephist(h);
           h2 = MyHist([5, 20, 120], 0:3)
           stairs!(h2)
           current_figure()
       end

Notice one is stephist the other is stairs!, that produce:

Notice, if we delete the color = C) part from the plot!() function above, the latest code plots the colors as expected:

asinghvi17 · March 22, 2024, 3:10pm

First you might try passing the attributes directly and not decomposing the observable, i.e., removing the [].

If you need to modify them you can do it through lift.

Pass all the attributes to stairs but delete the ones which don’t belong. We ought to have a merge function for this but you can do something like the following:

# plot = input plot
scene = Makie.parent_scene(plot)
stephist_default = Makie.default_theme(scene, Makie.StepHist)
for key in keys(stephist_default)
stephist_default[key] = get(plot.attributes, key, stephist_default[key])
end
stephist!(scene, input, attributes)
end

jling · March 22, 2024, 3:57pm

what’s the relationship between the plot in your definition and the input (I assume your input is the same as my input)?

asinghvi17 · March 22, 2024, 4:00pm

ah sorry in this case plot is just the argument passed to the function, my phrasing was probably a bit off

jling · March 22, 2024, 4:03pm

no worries, I still can’t quite get it to work:

function Makie.plot!(plot::StepHist{<:Tuple{<:MyHist}})
    scene = Makie.parent_scene(plot)
    attributes = Makie.default_theme(scene, Makie.Stairs)
    for key in keys(stephist_default)
        attributes[key] = get(plot.attributes, key, attributes[key])
    end
    stairs!(scene, plot, attributes)
    plot
end

notice I’m eventually calling stairs!(), I think you had a typo in your example, I also fixed the input on the last line which wasn’t define in your first snippet

jling · March 22, 2024, 5:14pm

@asinghvi17 specifically, I think the defined convert rule is not used correctly in this code path.

I get:

julia> Makie.convert_arguments(P::Type{<:Stairs}, h::MyHist) = convert_arguments(P, h.binedges, [0; h.bincounts])

julia> begin
           stephist(h);
           h2 = MyHist([5, 20, 120], 0:3)
           stairs!(h2)
           current_figure()
       end
ERROR: `Makie.convert_arguments` for the plot type Plot{Makie.stairs} and its conversion trait PointBased() was unsuccessful.

The signature that could not be converted was:
::Plot{Makie.stephist, Tuple{MyHist}}, ::Attributes

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://docs.makie.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.

Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] convert_arguments(::Type{Plot{Makie.stairs}}, ::Plot{Makie.stephist, Tuple{MyHist}}, ::Vararg{Any}; kw::@Kwargs{})
    @ Makie ~/Documents/github/Makie.jl/src/conversions.jl:17
  [3] convert_arguments(::Type{Plot{Makie.stairs}}, ::Plot{Makie.stephist, Tuple{MyHist}}, ::Attributes)
    @ Makie ~/Documents/github/Makie.jl/src/conversions.jl:7
  [4] (Plot{Makie.stairs})(args::Tuple{Plot{Makie.stephist, Tuple{MyHist}}, Attributes}, plot_attributes::Dict{Symbol, Any})
    @ Makie ~/Documents/github/Makie.jl/src/interfaces.jl:139
  [5] _create_plot!(::Function, ::Dict{Symbol, Any}, ::Scene, ::Plot{Makie.stephist, Tuple{MyHist}}, ::Vararg{Any})
    @ Makie ~/Documents/github/Makie.jl/src/figureplotting.jl:289

asinghvi17 · March 22, 2024, 6:33pm

stairs!(plot, input, attributes)

is probably what you want here, where input is whatever you’ve processed from plot.converted.

Alternatively you can return a PlotSpec from the convert method if you don’t need to set anything complex up…

jling · March 22, 2024, 9:08pm

sorry I don’t understand what does this mean, I tried the following:

julia> struct MyHist
           bincounts
           binedges
       end

julia> h = MyHist([1, 10, 100], 0:3)
MyHist([1, 10, 100], 0:3)

julia> Makie.convert_arguments(P::Type{<:Stairs}, h::MyHist) = convert_arguments(P, h.binedges, [0; h.bincounts])

julia> function Makie.plot!(plot::StepHist{<:Tuple{<:MyHist}})
           scene = Makie.parent_scene(plot)
           attributes = Makie.default_theme(scene, Makie.Stairs)
           for key in keys(attributes)
               attributes[key] = get(plot.attributes, key, attributes[key])
           end
           stairs!(plot, plot.converted, attributes)
           plot
       end

julia> begin
           stephist(h);
           h2 = MyHist([5, 20, 120], 0:3)
           stairs!(h2)
           current_figure()
       end
ERROR: `Makie.convert_arguments` for the plot type Plot{Makie.stairs} and its conversion trait PointBased() was unsuccessful.

The signature that could not be converted was:
::Tuple{Observable{MyHist}}, ::Attributes

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://docs.makie.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.

jling · March 22, 2024, 9:11pm

ok I think attributes needs to be the second argument:

julia> function Makie.plot!(plot::StepHist{<:Tuple{<:MyHist}})
           scene = Makie.parent_scene(plot)
           attributes = Makie.default_theme(scene, Makie.Stairs)
           for key in keys(attributes)
               attributes[key] = get(plot.attributes, key, attributes[key])
           end
           stairs!(plot, attributes, plot[1])
           plot
       end