infer dodge width from barplots

Project.toml

@@ -4,6 +4,7 @@ authors = ["Pietro Vertechi", "Julius Krumbiegel"]
 version = "0.8.7"
 
 [deps]
+Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"
 Colors = "5ae59095-9a9b-59fe-a467-6f913c188581"
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
 Dictionaries = "85a47980-9c8c-11e8-2b9f-f7ca1fa99fb4"

src/AlgebraOfGraphics.jl

@@ -22,6 +22,7 @@ using Dictionaries: AbstractDictionary, Dictionary, Indices, getindices, set!, d
 using KernelDensity: kde, pdf
 using StatsBase: fit, histrange, Histogram, normalize, sturges, StatsBase
 
+import Accessors
 import GLM, Loess
 import FileIO
 import RelocatableFolders

src/algebra/layers.jl

@@ -276,6 +276,8 @@ function compute_axes_grid(d::AbstractDrawable, scales::Scales = scales(); axis=
         map!(fitscale, scaledict, scaledict)
     end
 
+    set_dodge_width_default!(categoricalscales, processedlayers)
+
     pls_grid = compute_processedlayers_grid(processedlayers, categoricalscales)
     entries_grid, continuousscales_grid, merged_continuousscales =
         compute_entries_continuousscales(pls_grid, categoricalscales, scale_props)
@@ -504,6 +506,8 @@ function Base.show(io::IO, layers::Layers; indent = 0)
     end
 end
 
+scale_setting_name(scale_id, aes::Type{<:Aesthetic}) = scale_id !== nothing ? scale_id : string(nameof(aes))[4:end]
+
 function compute_dodge(data, key::Symbol, dodgevalues, scale_mapping, categoricalscales, dodge_aes)
     scale_id = get(scale_mapping, key, nothing)
     scale = categoricalscales[dodge_aes][scale_id]
@@ -516,9 +520,83 @@ function compute_dodge(data, key::Symbol, dodgevalues, scale_mapping, categorica
     width = if props.width !== nothing
         props.width
     else
-        error("Tried to compute dodging offsets but the `width` attribute of the dodging scale was `nothing`. This happens if only plots participate in the dodge that do not have an inherent width. For example, a scatter plot has no width but a barplot does. You can pass a width manually via the settings for `$(scale_id !== nothing ? scale_id : string(nameof(dodge_aes))[4:end])` in the `scales()` function.")
+        error("Tried to compute dodging offsets but the `width` attribute of the dodging scale was `nothing`. This happens if only plots participate in the dodge that do not have an inherent width. For example, a scatter plot has no width but a barplot does. You can pass a width manually like `draw(..., scales($(scale_setting_name(scale_id, dodge_aes)) = (; width = 0.6))`.")
     end
     # scale to 0-1, center around 0, shrink to width (like centers of bins that added together result in width)
     offsets = ((indices .- 1) ./ (n - 1) .- 0.5) .* width * (n-1) / n
     return data .+ offsets
-end
+end
+
+function set_dodge_width_default!(categoricalscales, processedlayers)
+    for dodgetype in (AesDodgeX, AesDodgeY)
+        haskey(categoricalscales, dodgetype) || continue
+        scales = categoricalscales[dodgetype]
+        for (scale_id, scale) in pairs(scales)
+            props = scale.props.aesprops
+            props.width === nothing || continue
+            n_dodge = length(datavalues(scale))
+            width::Union{Float64,Nothing} = nothing
+            for p in processedlayers
+                _width = determine_dodge_width(p, dodgetype, n_dodge)
+                if width === nothing
+                    width = _width
+                elseif _width !== nothing
+                    width == _width || error("Determined at least two different auto-widths for the `$(scale_setting_name(scale_id, dodgetype))` scale, $width and $_width. AlgebraOfGraphics tried to determine dodge with because you specified that a width-less plot type such as Scatter or Errorbars should be dodged. Some plot types like Barplot may have an inherent width for dodging which can often be auto-determined, so AlgebraOfGraphics looked for such widths in all other plot types in this plot. Because multiple such widths were detected, AlgebraOfGraphics gives up and you have to specify the dodge width for your width-less plots manually, like `draw(..., scales($(scale_setting_name(scale_id, dodgetype)) = (; width = 0.5))`")
+                end
+            end
+            if width !== nothing
+                scales[scale_id] = update_width(scale, width)
+            end
+        end
+    end
+    return
+end
+
+function update_width(scale::CategoricalScale, width)
+    return Accessors.@set scale.props.aesprops.width = width
+end
+
+function determine_dodge_width(p::ProcessedLayer, dodgetype, n_dodge)::Union{Float64,Nothing}
+    aes_mapping = aesthetic_mapping(p)
+    for key in keys(p.primary)
+        aes = hardcoded_or_mapped_aes(p, key, aes_mapping)
+        # check that processedlayer participates in this dodge
+        aes == dodgetype || continue
+        return determine_dodge_width(p.plottype, p, aes_mapping, dodgetype, n_dodge)
+    end
+    return nothing
+end
+
+determine_dodge_width(anyplot, p::ProcessedLayer, aes_mapping, dodgetype, n_dodge) = nothing
+
+attribute_or_plot_default(plottype, attributes, key) = get(attributes, key) do
+    to_value(Makie.default_theme(nothing, plottype)[key])
+end
+
+function determine_dodge_width(T::Type{BarPlot}, p::ProcessedLayer, aes_mapping, dodgetype, n_dodge)
+    width = attribute_or_plot_default(T, p.attributes, :width)
+    gap = attribute_or_plot_default(T, p.attributes, :gap)
+    dodge_gap = attribute_or_plot_default(T, p.attributes, :dodge_gap)
+    gap_scaler = dodge_gap / (n_dodge - 1) * 1.5 # why 1.5?
+    if width === Makie.automatic
+        corresponding_aes(::Type{AesDodgeX}) = AesX
+        corresponding_aes(::Type{AesDodgeY}) = AesY
+        if length(p.positional) == 1 # Makie goes 1:n automatically if only one arg is given
+            return (1.0 - gap + gap_scaler)
+        end
+        for key in eachindex(p.positional)
+            if aes_mapping[key] === corresponding_aes(dodgetype)
+                return resolution(p.positional[key]) * (1 - gap + gap_scaler)
+            end
+        end
+    elseif width isa Real
+        return width * (1 - gap + gap_scaler)
+    end
+    return
+end
+
+function resolution(vec_of_vecs)::Float64
+    iscategoricalcontainer(vec_of_vecs) && return 1.0
+    s = unique(sort(reduce(vcat, vec_of_vecs)))
+    return minimum((b - a for (a, b) in @views zip((s[begin:end-1]), s[begin+1:end])))
+end

test/reference_tests.jl

@@ -900,5 +900,48 @@ reftest("title subtitle footnotes fontsize inherit") do
         ),
         axis = (; width = 100, height = 100)
     )
+end
+
+reftest("dodge barplot with errorbars") do 
+    f = Figure()
+    df = (
+        x = [1, 1, 2, 2],
+        y = [1, 2, 5, 6],
+        err = [0.5, 0.4, 0.7, 0.6],
+        group = ["A", "B", "A", "C"],
+    )
+
+    function spec(; kwargs...)
+        xdir = get(kwargs, :direction, :y) == :x
+        dodge_map = xdir ? mapping(dodge_y = :group) : mapping(dodge_x = :group)
+        return data(df) * (
+            mapping(:x, :y, dodge = :group, color = :group) * visual(BarPlot; kwargs...) +
+            mapping(xdir ? :y : :x, xdir ? :x : :y, :err) * dodge_map * visual(Errorbars; direction = xdir ? :x : :y)
+        )
+    end
+
+    draw!(f[1, 1], spec())
+    draw!(f[1, 2], spec(; width = 0.7, dodge_gap = 0.2))
+    draw!(f[2, 1], spec(; direction = :x))
+    draw!(f[2, 2], spec(; direction = :x, width = 0.7, gap = 0.3, dodge_gap = 0.2))
+    f
+end
+
+reftest("dodge scatter with rangebars") do
+    df = (
+        x = repeat(1:10, inner = 2),
+        y = cos.(range(0, 2pi, length = 20)),
+        ylow = cos.(range(0, 2pi, length = 20)) .- 0.2,
+        yhigh = cos.(range(0, 2pi, length = 20)) .+ 0.3,
+        dodge = repeat(["A", "B"], 10)
+    )
 
-end
+    f = Figure()
+    spec1 = data(df) * (mapping(:x, :y, dodge_x = :dodge, color = :dodge) * visual(Scatter) + mapping(:x, :ylow, :yhigh, dodge_x = :dodge, color = :dodge) * visual(Rangebars))
+    spec2 = data(df) * (mapping(:y, :x, dodge_y = :dodge, color = :dodge) * visual(Scatter) + mapping(:x, :ylow, :yhigh, dodge_y = :dodge, color = :dodge) * visual(Rangebars, direction = :x))
+    draw!(f[1, 1], spec1, scales(DodgeX = (; width = 0.5)))
+    draw!(f[1, 2], spec2, scales(DodgeY = (; width = 0.5)))
+    draw!(f[2, 1], spec1, scales(DodgeX = (; width = 1.0)))
+    draw!(f[2, 2], spec2, scales(DodgeY = (; width = 1.0)))
+    f
+end