added violin plot

src/Plots.jl

@@ -68,6 +68,8 @@ export
     abline!,
     boxplot,
     boxplot!,
+    violin,
+    violin!,
 
     title!,
     xlabel!,
@@ -192,6 +194,8 @@ scatter3d(args...; kw...)  = plot(args...; kw...,  linetype = :scatter3d)
 scatter3d!(args...; kw...) = plot!(args...; kw..., linetype = :scatter3d)
 boxplot(args...; kw...)    = plot(args...; kw...,  linetype = :box)
 boxplot!(args...; kw...)   = plot!(args...; kw..., linetype = :box)
+violin(args...; kw...)     = plot(args...; kw...,  linetype = :violin)
+violin!(args...; kw...)    = plot!(args...; kw..., linetype = :violin)
 
 
 title!(s::AbstractString; kw...)                 = plot!(; title = s, kw...)

src/args.jl

@@ -11,7 +11,7 @@ const _3dTypes = [:path3d, :scatter3d, :surface, :wireframe]
 const _allTypes = vcat([
                         :none, :line, :path, :steppre, :steppost, :sticks, :scatter,
                         :heatmap, :hexbin, :hist, :hist2d, :hist3d, :density, :bar, :hline, :vline, :ohlc,
-                        :contour, :pie, :shape, :box
+                        :contour, :pie, :shape, :box, :violin
                        ], _3dTypes)
 @compat const _typeAliases = KW(
     :n             => :none,

src/backends/supported.jl

@@ -80,7 +80,7 @@ supportedArgs(::GadflyBackend) = [
   ]
 supportedAxes(::GadflyBackend) = [:auto, :left]
 supportedTypes(::GadflyBackend) = [:none, :line, :path, :steppre, :steppost, :sticks,
-                                   :scatter, :hist2d, :hexbin, :hist, :bar, :box,
+                                   :scatter, :hist2d, :hexbin, :hist, :bar, :box, :violin,
                                    :hline, :vline, :contour, :shape]
 supportedStyles(::GadflyBackend) = [:auto, :solid, :dash, :dot, :dashdot, :dashdotdot]
 supportedMarkers(::GadflyBackend) = vcat(_allMarkers, Shape)
@@ -167,7 +167,7 @@ supportedArgs(::PyPlotBackend) = [
   ]
 supportedAxes(::PyPlotBackend) = _allAxes
 supportedTypes(::PyPlotBackend) = [:none, :line, :path, :steppre, :steppost, #:sticks,
-                                   :scatter, :hist2d, :hexbin, :hist, :density, :bar, :box,
+                                   :scatter, :hist2d, :hexbin, :hist, :density, :bar, :box, :violin,
                                    :hline, :vline, :contour, :path3d, :scatter3d, :surface, :wireframe, :heatmap]
 supportedStyles(::PyPlotBackend) = [:auto, :solid, :dash, :dot, :dashdot]
 # supportedMarkers(::PyPlotBackend) = [:none, :auto, :rect, :ellipse, :diamond, :utriangle, :dtriangle, :cross, :xcross, :star5, :hexagon]

src/recipes.jl

@@ -43,6 +43,8 @@ apply_series_recipe(d::KW, lt) = KW[d]
 # -------------------------------------------------
 # Box Plot
 
+const _box_halfwidth = 0.4
+
 function apply_series_recipe(d::KW, ::Type{Val{:box}})
     # dumpdict(d, "box before", true)
     # TODO: add scatter series with outliers
@@ -58,7 +60,7 @@ function apply_series_recipe(d::KW, ::Type{Val{:box}})
         q1,q2,q3,q4,q5 = quantile(d[:y][groupby.groupIds[i]], linspace(0,1,5))
 
         # make the shape
-        l, m, r = i - 0.3, i, i + 0.3
+        l, m, r = i - _box_halfwidth, i, i + _box_halfwidth
         xcoords = [
             m, l, r, m, m, NaN,         # lower T
             l, l, r, r, l, NaN,         # lower box
@@ -80,6 +82,58 @@ function apply_series_recipe(d::KW, ::Type{Val{:box}})
     KW[d]
 end
 
+# -------------------------------------------------
+# Violin Plot
+
+try
+    Pkg.installed("KernelDensity")
+    import KernelDensity
+
+    warn("using KD for violin")
+    function violin_coords(y)
+        kd = KernelDensity.kde(y, npoints = 30)
+        kd.density, kd.x
+    end
+catch
+    warn("using hist for violin")
+    function violin_coords(y)
+        edges, widths = hist(y, 20)
+        centers = 0.5 * (edges[1:end-1] + edges[2:end])
+        ymin, ymax = extrema(y)
+        vcat(0.0, widths, 0.0), vcat(ymin, centers, ymax)
+    end
+end
+
+
+function apply_series_recipe(d::KW, ::Type{Val{:violin}})
+    # dumpdict(d, "box before", true)
+    # TODO: add scatter series with outliers
+
+    # create a list of shapes, where each shape is a single boxplot
+    shapes = Shape[]
+    d[:linetype] = :shape
+    groupby = extractGroupArgs(d[:x])
+
+    for (i, glabel) in enumerate(groupby.groupLabels)
+
+        # get the edges and widths
+        y = d[:y][groupby.groupIds[i]]
+        widths, centers = violin_coords(y)
+
+        # normalize
+        widths = _box_halfwidth * widths / maximum(widths)
+
+        # make the violin
+        xcoords = vcat(widths, -reverse(widths)) + i
+        ycoords = vcat(centers, reverse(centers))
+        push!(shapes, Shape(xcoords, ycoords))
+    end
+
+    d[:x], d[:y] = shape_coords(shapes)
+    d[:plotarg_overrides] = KW(:xticks => (1:length(shapes), groupby.groupLabels))
+
+    KW[d]
+end
 
 # -------------------------------------------------