Scale.alpha_continuous and Scale.alpha_discrete

NEWS.md

@@ -3,6 +3,7 @@ This is a log of major changes in Gadfly between releases. It is not exhaustive.
 Each release typically has a number of minor bug fixes beyond what is listed here.
 
 # Version 1.1.0
+ * Add `alpha` aesthetic, `Scale.alpha_continuous` and `Scale.alpha_discrete` (#1252)
  * Add `limits=(min= , max= )` to `Stat.histogram` (#1249)
  * Add dodged boxplots (#1246)
  * Add `Stat.dodge` (#1240) 

docs/src/gallery/geometries.md

@@ -412,13 +412,13 @@ x = -4:0.1:4
 Da = [DataFrame(x=0:0.1:20, y=X[:,j], ymin=X[:,j].-0.5, ymax=X[:,j].+0.5, f="$f")  for (j,f) in enumerate(["cos","sin"])]
 Db = [DataFrame(x=x, ymax=pdf.(Normal(μ),x), ymin=0.0, u="μ=$μ") for μ in [-1,1] ]
 
-# In the line below, 0.4 is the color opacity
-p1 = plot(vcat(Da...), x=:x, y=:y, ymin=:ymin, ymax=:ymax, color=:f, Geom.line, Geom.ribbon,
-    Theme(lowlight_color=c->RGBA{Float32}(c.r, c.g, c.b, 0.4))
+# In the line below, 0.6 is the color opacity
+p1 = plot(vcat(Da...), x=:x, y=:y, ymin=:ymin, ymax=:ymax, color=:f, 
+    Geom.line, Geom.ribbon, Theme(alphas=[0.6])
 )
-p2 = plot(vcat(Db...), x = :x, y=:ymax, ymin = :ymin, ymax = :ymax, color = :u, 
+p2 = plot(vcat(Db...), x = :x, y=:ymax, ymin = :ymin, ymax = :ymax, 
+    color = :u, alpha=:u, Theme(alphas=[0.8,0.2]),
     Geom.line, Geom.ribbon, Guide.ylabel("Density"),
-    Theme(lowlight_color=c->RGBA{Float32}(c.r, c.g, c.b, 0.4)), 
     Guide.colorkey(title="", pos=[2.5,0.6]), Guide.title("Parametric PDF")
 )
 hstack(p1,p2)

docs/src/gallery/scales.md

@@ -1,5 +1,49 @@
 # Scales
 
+## [`Scale.alpha_continuous`](@ref)
+
+```@example
+using Gadfly
+set_default_plot_size(21cm, 8cm)
+palettef = Scale.lab_gradient("darkgreen", "orange", "blue")
+p1 = plot(x=1:10, y=rand(10), color=[1:10;], Geom.point,  
+    Scale.color_continuous(colormap=palettef, minvalue=0, maxvalue=10),
+    Guide.title("Scale.color_continuous, Theme(alphas=[0.5])"),
+    Theme(alphas=[0.5], continuous_highlight_color=identity,
+        point_size=2mm)
+)
+p2 = plot(x=1:10, y=rand(10), alpha=[1:10;], Geom.point,  
+    Scale.alpha_continuous(minvalue=0, maxvalue=10),
+    Guide.title("Scale.alpha_continuous, Theme(default_color=\"blue\")"),
+    Theme(default_color="blue", discrete_highlight_color=c->"gray",
+        point_size=2mm)
+)
+hstack(p1, p2)
+```
+
+## [`Scale.alpha_discrete`](@ref)
+
+```@example
+using DataFrames, Gadfly
+set_default_plot_size(21cm, 8cm)
+D = DataFrame(x=1:6, y=rand(6), Shape=repeat(["a","b","c"], outer=2))
+coord = Coord.cartesian(xmin=0, xmax=7, ymin=0, ymax=1.0)
+p1 = plot(D, x=:x, y=:y, color=:x,  coord,
+    Scale.color_discrete, Geom.point, Geom.hair,
+    Guide.title("Scale.color_discrete, Theme(alphas=[0.5])"),
+    Theme(alphas=[0.5], discrete_highlight_color=identity,
+        point_size=2mm)
+)
+p2 = plot(D, x=:x, y=:y, alpha=:x, shape=:Shape, coord,
+    Scale.alpha_discrete, Geom.point, Geom.hair,
+    Guide.title("Scale.alpha_discrete, Theme(default_color=\"green\")"),
+    Theme(default_color="green",   discrete_highlight_color=c->"gray",
+        point_size=2mm, alphas=[0.0,0.2,0.4,0.6,0.8,1.0])
+)
+hstack(p1,p2)
+```
+
+
 ## [`Scale.color_continuous`](@ref)
 
 ```@example

docs/src/gallery/statistics.md

@@ -19,17 +19,15 @@ using Colors, DataFrames, Gadfly, Distributions
 set_default_plot_size(21cm, 8cm)
 x = -4:0.1:4
 Da = [DataFrame(x=x, ymax=pdf.(Normal(μ),x), ymin=0.0, u="μ=$μ") for μ in [-1,1]]
-Db = [DataFrame(x=randn(200).+μ, u="μ=$μ") for μ in [-1,1]] 
+Db = [DataFrame(x=randn(200).+μ, u="μ=$μ") for μ in [-1,1]]
 
 p1 = plot(vcat(Da...), x=:x, y=:ymax, ymin=:ymin, ymax=:ymax, color=:u, 
-    Geom.line, Geom.ribbon, Guide.ylabel("Density"),
-    Theme(lowlight_color=c->RGBA{Float32}(c.r, c.g, c.b, 0.4)), 
+    Geom.line, Geom.ribbon, Guide.ylabel("Density"), Theme(alphas=[0.6]), 
     Guide.colorkey(title="", pos=[2.5,0.6]), Guide.title("Parametric PDF")
 )
-p2 = plot(vcat(Db...), x=:x, color=:u, 
+p2 = plot(vcat(Db...), x=:x, color=:u, Theme(alphas=[0.6]), 
     Stat.density(bandwidth=0.5), Geom.polygon(fill=true, preserve_order=true),
-    Coord.cartesian(xmin=-4, xmax=4),
-    Theme(lowlight_color=c->RGBA{Float32}(c.r, c.g, c.b, 0.4)),
+    Coord.cartesian(xmin=-4, xmax=4, ymin=0, ymax=0.4),
     Guide.colorkey(title="", pos=[2.5,0.6]), Guide.title("Kernel PDF")
 )
 hstack(p1,p2)
@@ -88,8 +86,7 @@ p = plot(salaries[salaries.Rank.=="Prof",:], x=:YrsService, y=:Salary,
   layer(Stat.smooth(method=:lm, levels=[0.95, 0.99]), Geom.line, Geom.ribbon)), 
     Scale.xgroup(levels=["Discipline A", "Discipline B"]),
     Guide.colorkey(title="", pos=[0.43w, -0.4h]), 
-    Theme(point_size=2pt,
-        lowlight_color=c->RGBA{Float32}(c.r, c.g, c.b, 0.2) )
+    Theme(point_size=2pt, alphas=[0.5] )
 )
 ```
 

docs/src/tutorial.md

@@ -171,7 +171,8 @@ All aesthetics (e.g. `x`, `y`, `color`) have a Scale e.g. `Scale.x_continuous()`
 | `x` | `x_continuous` | `xticks` |
 | `y` | `y_continuous` | `yticks` |
 | `color` | `color_continuous` | `colorkey` |
-| `size` | `size_continuous` | sizekey (tbd) |
+| `size`  | `size_continuous`  | sizekey (tbd)  |
+| `alpha` | `alpha_continuous` | alphakey (tbd) | 
 
 e.g. `Scale.x_continuous(format= , minvalue= , maxvalue= )`\
 `format` can be: `:plain`, `:scientific`, `:engineering`, or `:auto`.
@@ -213,7 +214,8 @@ hstack(p3, p4)
 | `shape` | `shape_discrete` | `shapekey` |
 | `size` | `size_discrete` | sizekey (tbd) |
 | `linestyle` | `linestyle_discrete` | linekey (tbd) |
-| `group` | `group_discrete` |  |
+| `alpha`  | `alpha_discrete` | alphakey (tbd) |
+| `group`  | `group_discrete` |  |
 | `xgroup` | `xgroup` |  |
 | `ygroup` | `ygroup` |  |
 
@@ -236,6 +238,7 @@ hstack(p5, p6)
 If you don't supply Scales or Guides, Gadfly will make an educated guess.
 
 ```@example 1
+set_default_plot_size(14cm, 8cm) # hide
 gasoline = dataset("Ecdat", "Gasoline")
 plot(gasoline, x=:Year, y=:LGasPCar, color=:Country, Geom.point, Geom.line)
 ```

src/Gadfly.jl

@@ -1146,6 +1146,7 @@ const default_aes_scales = Dict{Symbol, Dict}(
         :size        => Scale.size_continuous(),
         :group       => Scale.group_discrete(),
         :label       => Scale.label(),
+        :alpha       => Scale.alpha_continuous(),
         :linestyle   => Scale.linestyle_discrete()
     ),
 
@@ -1166,6 +1167,7 @@ const default_aes_scales = Dict{Symbol, Dict}(
         :size       => Scale.size_discrete(),
         :group      => Scale.group_discrete(),
         :label      => Scale.label(),
+        :alpha      => Scale.alpha_discrete(),
         :linestyle  => Scale.linestyle_discrete()
     )
 )

src/aesthetics.jl

@@ -18,6 +18,7 @@ const NumericalAesthetic =
     size,         Union{CategoricalAesthetic,Vector,Nothing}
     shape,        Union{CategoricalAesthetic,Vector,Nothing}
     color,        Union{CategoricalAesthetic,Vector,Nothing}
+    alpha,        NumericalOrCategoricalAesthetic
     linestyle,    Union{CategoricalAesthetic,Vector,Nothing}
 
     label,        CategoricalAesthetic

src/data.jl

@@ -38,6 +38,7 @@
     color
     group
     label
+    alpha
     func
     titles, Dict{Symbol, AbstractString}, Dict{Symbol, AbstractString}()
 end

src/geom/point.jl

@@ -28,7 +28,7 @@ Draw scatter plots of the `x` and `y` aesthetics.
 """
 const point = PointGeometry
 
-element_aesthetics(::PointGeometry) = [:x, :y, :size, :color, :shape]
+element_aesthetics(::PointGeometry) = [:x, :y, :size, :color, :shape, :alpha]
 
 # Generate a form for a point geometry.
 #
@@ -48,6 +48,7 @@ function render(geom::PointGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics
     default_aes.shape = Function[Shape.circle]
     default_aes.color = discretize_make_ia(RGBA{Float32}[theme.default_color])
     default_aes.size = Measure[theme.point_size]
+    default_aes.alpha = [theme.alphas[1]]
     aes = inherit(aes, default_aes)
 
     if eltype(aes.size) <: Int
@@ -57,9 +58,11 @@ function render(geom::PointGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics
       interpolate_size(x) = theme.point_size_min + (x-size_min) / size_range * point_size_range
     end
 
+    aes_alpha = eltype(aes.alpha) <: Int ? theme.alphas[aes.alpha] : aes.alpha
+
     ctx = context()
 
-    for (x, y, color, size, shape) in Compose.cyclezip(aes.x, aes.y, aes.color, aes.size, aes.shape)
+    for (x, y, color, size, shape, alpha) in Compose.cyclezip(aes.x, aes.y, aes.color, aes.size, aes.shape, aes_alpha)
         shapefun = typeof(shape) <: Function ? shape : theme.point_shapes[shape]
         sizeval = typeof(size) <: Int ? interpolate_size(size) : size
         strokecolor = aes.color_key_continuous != nothing && aes.color_key_continuous ?
@@ -68,7 +71,8 @@ function render(geom::PointGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics
         class = svg_color_class_from_label(aes.color_label([color])[1])
         compose!(ctx, (context(),
               (context(), shapefun([x], [y], [sizeval]), svgclass("marker")),
-              fill(color), stroke(strokecolor), svgclass(class)))
+              fill(color), stroke(strokecolor), fillopacity(alpha),
+               svgclass(class)))
     end
 
     compose!(ctx, linewidth(theme.highlight_width))

src/geom/polygon.jl

@@ -54,13 +54,14 @@ function render(geom::PolygonGeometry, theme::Gadfly.Theme, aes::Gadfly.Aestheti
     default_aes.group = IndirectArray(fill(1,length(aes.x)))
     default_aes.color = fill(theme.default_color, length(aes.x))
     default_aes.linestyle = fill(1, length(aes.x))
+    default_aes.alpha = fill(1, length(aes.x))
     aes = inherit(aes, default_aes)
 
-    aes_x, aes_y, aes_color, aes_linestyle, aes_group = concretize(aes.x, aes.y, aes.color, aes.linestyle, aes.group)
+    aes_x, aes_y, aes_color, aes_linestyle, aes_group, aes_alpha = concretize(aes.x, aes.y, aes.color, aes.linestyle, aes.group, aes.alpha)
 
-    XT, YT, CT, GT, LST = eltype(aes_x), eltype(aes_y), eltype(aes_color), eltype(aes_group), eltype(aes_linestyle)
+    XT, YT, CT, GT, LST, AT = eltype(aes_x), eltype(aes_y), eltype(aes_color), eltype(aes_group), eltype(aes_linestyle), eltype(aes_alpha)
 
-    groups = collect((Tuple{CT, GT, LST}), zip(aes_color, aes_group, aes_linestyle))
+    groups = collect((Tuple{CT, GT, LST, AT}), zip(aes_color, aes_group, aes_linestyle, aes_alpha))
     ug = unique(groups)
 
     n = length(ug)
@@ -69,20 +70,25 @@ function render(geom::PolygonGeometry, theme::Gadfly.Theme, aes::Gadfly.Aestheti
     colors = Vector{CT}(undef, n)
     line_styles = Vector{LST}(undef, n)
     linestyle_palette_length = length(theme.line_style)
+    alphas = Vector{Float64}(undef, n)
+    alpha_discrete  = AT <: Int
+
     for (k,g) in enumerate(ug)
         i = groups.==[g]
         polys[k] = polygon_points(aes_x[i], aes_y[i], geom.preserve_order)
         colors[k] = first(aes_color[i])
         line_styles[k] = mod1(first(aes_linestyle[i]), linestyle_palette_length) 
+        alphas[k] = first(alpha_discrete ? theme.alphas[aes_alpha[i]] : aes_alpha[i])
     end
 
     plinestyles = Gadfly.get_stroke_vector.(theme.line_style[line_styles])
     pcolors = theme.lowlight_color.(colors)
 
-    properties = geom.fill ? (fill(pcolors), stroke(theme.discrete_highlight_color.(colors))) :
+    properties = geom.fill ? (fill(pcolors), stroke(theme.discrete_highlight_color.(colors)), fillopacity(alphas)) :
         (fill(nothing), stroke(pcolors), strokedash(plinestyles))                
 
-    ctx = compose!(context(order=geom.order), Compose.polygon(polys, geom.tag), properties...)
+    ctx = context(order=geom.order)
+    compose!(ctx, Compose.polygon(polys, geom.tag), properties...)
 
     return compose!(ctx, linewidth(theme.line_width), svgclass("geometry"))
 end

src/geom/ribbon.jl

@@ -16,35 +16,36 @@ const ribbon = RibbonGeometry
 
 default_statistic(geom::RibbonGeometry) = geom.default_statistic
 
-element_aesthetics(::RibbonGeometry) = [:x, :ymin, :ymax, :color, :linestyle]
+element_aesthetics(::RibbonGeometry) = [:x, :ymin, :ymax, :color, :linestyle, :alpha]
 
 function render(geom::RibbonGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics)
     Gadfly.assert_aesthetics_defined("Geom.ribbon", aes, :x, :ymin, :ymax)
-    Gadfly.assert_aesthetics_equal_length("Geom.ribbon", aes,
-                                          element_aesthetics(geom)...)
+    Gadfly.assert_aesthetics_equal_length("Geom.ribbon", aes, element_aesthetics(geom)...)
 
     default_aes = Gadfly.Aesthetics()
     default_aes.linestyle = fill(1, length(aes.x))
     default_aes.color = fill(theme.default_color, length(aes.x))
+    default_aes.alpha = fill(1, length(aes.x))
     aes = inherit(aes, default_aes)
 
-    aes_x, aes_ymin, aes_ymax, aes_color, aes_linestyle = concretize(aes.x, aes.ymin, aes.ymax, aes.color, aes.linestyle)
-    XT, CT, LST = eltype(aes_x), eltype(aes_color), eltype(aes_linestyle)
+    aes_x, aes_ymin, aes_ymax, aes_color, aes_linestyle, aes_alpha = 
+        concretize(aes.x, aes.ymin, aes.ymax, aes.color, aes.linestyle, aes.alpha)
+    XT, CT, LST, AT = eltype(aes_x), eltype(aes_color), eltype(aes_linestyle), eltype(aes_alpha)
     YT = Float64
-    groups = collect((Tuple{CT, LST}), zip(aes_color, aes_linestyle))
+    groups = collect((Tuple{CT, LST, AT}), zip(aes_color, aes_linestyle, aes_alpha))
     ug = unique(groups)
 
     V = Vector{Tuple{XT, YT}}
-    K = Tuple{CT, LST}
+    K = Tuple{CT, LST, AT}
 
     max_points = Dict{K, V}(g=>V[] for g in ug)
-    for (x, y, c, ls) in zip(aes_x, aes_ymax, aes_color, aes_linestyle)
-        push!(max_points[(c,ls)], (x, y))
+    for (x, y, c, ls, a) in zip(aes_x, aes_ymax, aes_color, aes_linestyle, aes_alpha)
+        push!(max_points[(c,ls,a)], (x, y))
     end
 
     min_points = Dict{K, V}(g=>V[] for g in ug)
-    for (x, y, c, ls) in zip(aes_x, aes_ymin, aes_color, aes_linestyle)
-        push!(min_points[(c,ls)], (x, y))
+    for (x, y, c, ls, a) in zip(aes_x, aes_ymin, aes_color, aes_linestyle, aes_alpha)
+        push!(min_points[(c,ls,a)], (x, y))
     end
 
     for k in keys(max_points)
@@ -56,14 +57,22 @@ function render(geom::RibbonGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetic
     polys = [collect(Tuple{XT, YT}, Iterators.flatten((min_points[k], max_points[k]))) for k in kys]
     lines = [collect(Tuple{XT, YT}, Iterators.flatten((min_points[k], [(last(min_points[k])[1], NaN)], max_points[k]))) for k in kys]
 
-    colors = [theme.lowlight_color(c) for (c,ls) in kys]
-    linestyles = [Gadfly.get_stroke_vector(theme.line_style[ls]) for (c,ls) in kys]
+    n = length(kys)
+    colors = Vector{Union{Colorant, String}}(undef, n)
+    linestyles = Vector{Vector{Measure}}(undef, n)
+    alphas = Vector{Float64}(undef, n)
+    alpha_discrete  = AT <: Int
+
+    for (i, (c,ls,a)) in enumerate(kys)
+        colors[i] = theme.lowlight_color(c)
+        linestyles[i] = Gadfly.get_stroke_vector(theme.line_style[ls])
+        alphas[i] = alpha_discrete ? theme.alphas[a] : a
+    end
+
+    ctx = context()
 
-    ctx = geom.fill ? compose!(context(), Compose.polygon(polys, geom.tag), fill(colors)) : 
-        compose!(context(), Compose.line(lines, geom.tag), fill(nothing), stroke(colors), strokedash(linestyles))
+    geom.fill ? compose!(ctx, Compose.polygon(polys, geom.tag), fill(colors), fillopacity(alphas)) : 
+        compose!(ctx, Compose.line(lines, geom.tag), fill(nothing), stroke(colors), strokedash(linestyles))
 
-    return compose!(
-        ctx,
-        svgclass("geometry"),
-        linewidth(theme.line_width))
+    return compose!(ctx, svgclass("geometry"), linewidth(theme.line_width))
 end