Geom.bar update 1 (#1428)

* Geom.bar(position=:identity) plus alpha

NEWS.md

@@ -3,6 +3,7 @@ Each release typically has a number of minor bug fixes beyond what is listed her
 
 # Version 1.x
 
+* Add `Geom.bar(position=:identity)` + alpha enabled (#1428)
 * Enable stacked guides (#1423)
 
 

docs/src/gallery/geometries.md

@@ -41,9 +41,19 @@ plot(De, x=:Date, y=:Unemploy, Geom.line,
 ## [`Geom.bar`](@ref)
 
 ```@example
-using Gadfly, RDatasets
-set_default_plot_size(14cm, 8cm)
-plot(dataset("HistData", "ChestSizes"), x="Chest", y="Count", Geom.bar)
+using ColorSchemes, DataFrames, Distributions, Gadfly
+set_default_plot_size(21cm, 8cm)
+x = range(-4, 4, length=30)
+fn1(μ,x=x) = pdf.(Normal(μ, 1), x)
+D = [DataFrame(x=x, y=fn1(μ), μ="$(μ)") for μ in [-1, 1]]
+cpalette(p) = get(ColorSchemes.viridis, p)
+p1 = plot(D[1], y=:y, x=:x, color=0:29, Geom.bar,
+    Scale.color_continuous(colormap=cpalette),
+    Theme(bar_spacing=-0.2mm, key_position=:none))
+p2 = plot(D[1], x=:x, y=:y, Geom.bar, alpha=range(0.2,0.9, length=30))
+p3 = plot(vcat(D...), x=:x, y=:y, color=:μ, alpha=[0.5],
+    Geom.bar(position=:identity))
+hstack(p1, p2, p3)
 ```
 
 ```@example
@@ -273,13 +283,18 @@ set_default_plot_size(21cm, 16cm)
 D = dataset("ggplot2","diamonds")
 gamma = Gamma(2, 2)
 Dgamma = DataFrame(x=rand(gamma, 10^4))
-p1 = plot(D, x="Price", Geom.histogram)
-p2 = plot(D, x="Price", color="Cut", Geom.histogram)
-p3 = plot(D, x="Price", color="Cut", Geom.histogram(bincount=30))
-p4 = plot(Dgamma, Coord.cartesian(xmin=0, xmax=20),
-    layer(x->pdf(gamma, x), 0, 20, Geom.line, Theme(default_color="black")),
-    layer(x=:x, Geom.histogram(bincount=20, density=true, limits=(min=0,))),
-    Theme(default_color="bisque") )
+p1 = plot(D, x="Price", color="Cut", Geom.histogram)
+p2 = plot(D, x="Price", color="Cut", Geom.histogram(bincount=30))
+p3 = plot(Dgamma, Coord.cartesian(xmin=0, xmax=20),
+    layer(x->pdf(gamma, x), 0, 20, color=[colorant"black"]),
+    layer(x=:x, Geom.histogram(bincount=20, density=true, limits=(min=0,)),
+    color=[colorant"bisque"]))
+a = repeat([0.75, 0.85], outer=40) # opacity
+D2 = [DataFrame(x=rand(Normal(μ,1), 500), μ="$(μ)") for μ in [-1, 1]]
+p4 = plot(vcat(D2...), x=:x,  color=:μ, alpha=[a;a],
+    Geom.histogram(position=:identity, bincount=40, limits=(min=-4, max=4)),
+    Scale.color_discrete_manual("skyblue","moccasin")
+)
 gridstack([p1 p2; p3 p4])
 ```
 

src/geom/bar.jl

@@ -10,7 +10,7 @@ BarGeometry(; position=:stack, orientation=:vertical, tag=empty_tag) =
             orientation = orientation), tag)
 
 element_aesthetics(geom::BarGeometry) = geom.orientation == :vertical ?
-            [:xmin, :xmax, :y, :color] : [:ymin, :ymax, :x, :color]
+            [:xmin, :xmax, :y, :color, :alpha] : [:ymin, :ymax, :x, :color, :alpha]
 
 default_statistic(geom::BarGeometry) = geom.default_statistic
 
@@ -22,6 +22,7 @@ If orientation is `:horizontal` switch x for y.  Optionally categorically
 groups bars using the `color` aesthetic.  If `position` is `:stack` they will
 be placed on top of each other;  if it is `:dodge` they will be placed side by
 side.  For labelling dodged or stacked bar plots see [`Stat.dodge`](@ref).
+If `position` is `:identity` then the bars can overlap (use the `alpha` aesthetic).
 """
 const bar = BarGeometry
 
@@ -50,39 +51,34 @@ histogram(; position=:stack, bincount=nothing,
 # Render a single color bar chart
 function render_bar(geom::BarGeometry,
                               theme::Gadfly.Theme,
-                              aes::Gadfly.Aesthetics,
-                              orientation::Symbol)
-    if orientation == :horizontal
+                              aes::Gadfly.Aesthetics)
+    rect = if geom.orientation == :horizontal
         XT = eltype(aes.x)
         xz = convert(XT, zero(XT))
-        ctx = compose!(context(),
-            rectangle([min(xz, x) for x in aes.x],
-                      [ymin*cy - theme.bar_spacing/2 for ymin in aes.ymin],
-                      abs.(aes.x),
-                      [(ymax - ymin)*cy - theme.bar_spacing
-                       for (ymin, ymax) in zip(aes.ymin, aes.ymax)], geom.tag),
-            svgclass("geometry"))
+        rectangle(min.(xz, aes.x),
+            aes.ymin.*cy .- theme.bar_spacing/2,
+            abs.(aes.x),
+            (aes.ymax .- aes.ymin).*cy .- theme.bar_spacing, geom.tag)
     else
         YT = eltype(aes.y)
         yz = convert(YT, zero(YT))
-        ctx = compose!(context(),
-            rectangle([xmin*cx + theme.bar_spacing/2 for xmin in aes.xmin],
-                      [min(yz, y) for y in aes.y],
-                      [(xmax - xmin)*cx - theme.bar_spacing
-                       for (xmin, xmax) in zip(aes.xmin, aes.xmax)],
-                      abs.(aes.y), geom.tag),
-            svgclass("geometry"))
+        rectangle(aes.xmin.*cx .+ theme.bar_spacing/2,
+            min.(yz, aes.y),
+            (aes.xmax .- aes.xmin).*cx .- theme.bar_spacing, 
+            abs.(aes.y), geom.tag)
     end
 
-    cs = aes.color === nothing ? theme.default_color : aes.color
-    compose!(ctx, fill(cs), svgclass("geometry"))
-    if isa(theme.bar_highlight, Function)
-        compose!(ctx, stroke(theme.bar_highlight(theme.default_color)))
+    aes_alpha = eltype(aes.alpha) <: Int ? theme.alphas[aes.alpha] : aes.alpha
+    sc =  if isa(theme.bar_highlight, Function)
+        stroke(theme.bar_highlight(theme.default_color))
     elseif isa(theme.bar_highlight, Color)
-        compose!(ctx, stroke(theme.bar_highlight))
+        stroke(theme.bar_highlight)
     else
-        compose!(ctx, stroke(nothing))
+        stroke(nothing)
     end
+
+    ctx = context()
+    compose!(ctx, rect, fill(aes.color), sc, fillopacity(aes_alpha), svgclass("geometry"))
     return ctx
 end
 
@@ -272,8 +268,13 @@ function render(geom::BarGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics)
         error("Orientation must be :horizontal or :vertical")
     end
 
-    if aes.color === nothing
-        ctx = render_bar(geom, theme, aes, geom.orientation)
+    default_aes = Gadfly.Aesthetics()
+    default_aes.color = RGBA{Float32}[theme.default_color]
+    default_aes.alpha = Float64[theme.alphas[1]]
+    aes = inherit(aes, default_aes)    
+
+    if geom.position==:identity || length(aes.color)==1
+        ctx = render_bar(geom, theme, aes)
     elseif geom.position == :stack
         if geom.orientation == :horizontal
             for y in unique(aes.ymin)

test/testscripts/color_bar.jl

@@ -1,14 +1,14 @@
 using Gadfly
 
-set_default_plot_size(8inch, 3inch)
+set_default_plot_size(6inch, 8inch)
 
-dodge1 = plot(x=["a","a"], y=[3,2], color=["red","blue"],
-      Geom.bar(position=:dodge));
-dodge2 = plot(x=["a","a","b","b"], y=[3,2,1,2], color=["red","blue","red","blue"],
-      Geom.bar(position=:dodge));
-stack1 = plot(x=["a","a"], y=[3,2], color=["red","blue"],
-      Geom.bar(position=:stack));
-stack2 = plot(x=["a","a","b","b"], y=[3,2,1,2], color=["red","blue","red","blue"],
-      Geom.bar(position=:stack));
+c = ["red", "blue"]
+dodge1 = plot(x=["a","a"], y=[3,2], color=c, Geom.bar(position=:dodge))
+dodge2 = plot(x=["a","a","b","b"], y=[3,2,1,2], color=[c;c], Geom.bar(position=:dodge))
+stack1 = plot(x=["a","a"], y=[3,2], color=c, Geom.bar(position=:stack))
+stack2 = plot(x=["a","a","b","b"], y=[3,2,1,2], color=[c;c], Geom.bar(position=:stack))
+identity1 = plot(x=["a","a"], y=[3,2], color=c, alpha=[0.5], Geom.bar(position=:identity))
+identity2 = plot(x=["a","a","b","b"], y=[3,2,1,2], color=[c;c], alpha=[0.5],
+    Geom.bar(position=:identity))
 
-gridstack([dodge1 dodge2; stack1 stack2])
+gridstack([dodge1 dodge2; stack1 stack2; identity1 identity2])

test/testscripts/histogram_limits.jl

@@ -4,7 +4,7 @@ set_default_plot_size(6inch, 3inch)
 
 beta = Beta(2,2)
 Dbeta = DataFrame(x=rand(beta, 10^4))
-layer1 = layer(x->pdf(beta, x), 0, 1, Geom.line, Theme(default_color="black"))
+layer1 = layer(x->pdf(beta, x), 0, 1, Theme(default_color="black"))
 p1 = plot(Dbeta, layer1,
     layer(x=:x, Geom.histogram(bincount=20, density=true, limits=(min=0,))),
 )