make hist more flexible

docs/src/plotting_functions/hist.md

@@ -31,3 +31,17 @@ hist(data, normalization = :pdf, bar_labels = :values,
      label_formatter=x-> round(x, digits=2), label_size = 15,
      strokewidth = 0.5, strokecolor = (:black, 0.5), color = :values)
 ```
+
+#### Moving histograms
+
+With `scale_to`, and `offset`, one can put multiple histograms into the same plot.
+Note, that offset automatically sets fillto, to move the whole barplot.
+Also, one can use a negative `scale_to` amount to flip the histogram.
+```@example hist
+fig = Figure()
+ax = Axis(fig[1, 1])
+for i in 1:5
+     hist!(ax, randn(1000), scale_to=-0.6, offset=i, direction=:x)
+end
+fig
+```

src/basic_recipes/barplot.jl

@@ -13,6 +13,7 @@ $(ATTRIBUTES)
 @recipe(BarPlot, x, y) do scene
     Attributes(;
         fillto = automatic,
+        offset = 0.0,
         color = theme(scene, :patchcolor),
         colormap = theme(scene, :colormap),
         colorrange = automatic,
@@ -180,7 +181,7 @@ function Makie.plot!(p::BarPlot)
     label_aligns = Observable(Vec2f0[])
     label_offsets = Observable(Vec2f0[])
     label_colors = Observable(RGBAf0[])
-    function calculate_bars(xy, fillto, width, dodge, n_dodge, x_gap, dodge_gap, stack,
+    function calculate_bars(xy, fillto, offset, width, dodge, n_dodge, x_gap, dodge_gap, stack,
                             dir, bar_labels, flip_labels_at, label_color, color_over_background,
                             color_over_bar, label_formatter, label_offset)
 
@@ -208,10 +209,14 @@ function Makie.plot!(p::BarPlot)
 
         if stack === automatic
             if fillto === automatic
-                fillto = 0.0
+                fillto = offset
             end
         elseif eltype(stack) <: Integer
             fillto === automatic || @warn "Ignore keyword fillto when keyword stack is provided"
+            if !iszero(offset)
+                @warn "Ignore keyword offset when keyword stack is provided"
+                offset = 0.0
+            end
             i_stack = stack
 
             from, to = stack_grouped_from_to(i_stack, y, (x = x̂,))
@@ -233,10 +238,10 @@ function Makie.plot!(p::BarPlot)
             labels[], label_aligns[], label_offsets[], label_colors[] = label_args
         end
 
-        return bar_rectangle.(x̂, y, barwidth, fillto, in_y_direction)
+        return bar_rectangle.(x̂, y .+ offset, barwidth, fillto, in_y_direction)
     end
 
-    bars = lift(calculate_bars, p[1], p.fillto, p.width, p.dodge, p.n_dodge, p.x_gap,
+    bars = lift(calculate_bars, p[1], p.fillto, p.offset, p.width, p.dodge, p.n_dodge, p.x_gap,
                 p.dodge_gap, p.stack, p.direction, p.bar_labels, p.flip_labels_at,
                 p.label_color, p.color_over_background, p.color_over_bar, p.label_formatter, p.label_offset)
 

src/stats/hist.jl

@@ -28,6 +28,13 @@ can be normalized by setting `normalization`. Possible values are:
    norm 1.
 *  `:none`: Do not normalize.
 
+The following attributes can move the histogram around,
+which comes in handy when placing multiple histograms into one plot:
+* offset = 0.0: adds an offset to every value
+* fillto = 0.0: defines where the bar starts
+* scale_to = nothing: allows to scale all values to a certain height
+* flip = false: flips all values
+
 Color can either be:
 * a vector of `bins` colors
 * a single color
@@ -42,6 +49,9 @@ $(ATTRIBUTES)
         normalization = :none,
         cycle = [:color => :patchcolor],
         color = theme(scene, :patchcolor),
+        offset = 0.0,
+        fillto = automatic,
+        scale_to = nothing,
 
         bar_labels = nothing,
         flip_labels_at = Inf,
@@ -72,14 +82,17 @@ function Makie.plot!(plot::Hist)
         end
     end
 
-    points = lift(edges, plot.normalization) do edges, normalization
+    points = lift(edges, plot.normalization, plot.scale_to) do edges, normalization, scale_to
         h = StatsBase.fit(StatsBase.Histogram, values[], edges)
         h_norm = StatsBase.normalize(h, mode = normalization)
         centers = edges[1:end-1] .+ (diff(edges) ./ 2)
         weights = h_norm.weights
+        if !isnothing(scale_to)
+            max = maximum(weights)
+            weights .= weights ./ max .* scale_to
+        end
         return Point2f0.(centers, weights)
     end
-
     widths = lift(diff, edges)
     color = lift(plot.color) do color
         if color === :values
@@ -93,7 +106,7 @@ function Makie.plot!(plot::Hist)
         x === :values ? :y : x
     end
     # plot the values, not the observables, to be in control of updating
-    bp = barplot!(plot, points[]; width = widths[], plot.attributes..., bar_labels=bar_labels, color=color)
+    bp = barplot!(plot, points[]; width = widths[], plot.attributes..., fillto=plot.fillto, offset=plot.offset, bar_labels=bar_labels, color=color)
 
     # update the barplot points without triggering, then trigger with `width`
     on(widths) do w