barHack and histogramHack; now support bars and hists in Qwt; added examples

docs/example_generation.jl

@@ -43,6 +43,12 @@ const examples = PlotExample[
   PlotExample("Lots of line types",
               "Options: (:line, :step, :stepinverted, :sticks, :dots, :none, :heatmap, :hexbin, :hist, :bar)  \nNote: some may not work with all backends",
               [:(plot(rand(20,4); linetypes=[:line, :step, :sticks, :dots]))]),
+  PlotExample("Bar",
+              "x is the midpoint of the bar. (todo: allow passing of edges instead of midpoints)",
+              [:(bar(randn(1000)))]),
+  PlotExample("Histogram",
+              "note: fillto isn't supported on all backends",
+              [:(histogram(randn(1000); nbins=50, fillto=20))]),
 ]
 
 

docs/gadfly_examples.md

@@ -80,3 +80,23 @@ plot(rand(20,4); linetypes=[:line,:step,:sticks,:dots])
 
 ![](../img/gadfly_example_8.png)
 
+### Bar
+
+x is the midpoint of the bar. (todo: allow passing of edges instead of midpoints)
+
+```julia
+bar(randn(1000))
+```
+
+![](../img/gadfly_example_9.png)
+
+### Histogram
+
+note: fillto isn't supported on all backends
+
+```julia
+histogram(randn(1000); nbins=50,fillto=20)
+```
+
+![](../img/gadfly_example_10.png)
+

docs/qwt_examples.md

@@ -80,3 +80,23 @@ plot(rand(20,4); linetypes=[:line,:step,:sticks,:dots])
 
 ![](../img/qwt_example_8.png)
 
+### Bar
+
+x is the midpoint of the bar. (todo: allow passing of edges instead of midpoints)
+
+```julia
+bar(randn(1000))
+```
+
+![](../img/qwt_example_9.png)
+
+### Histogram
+
+note: fillto isn't supported on all backends
+
+```julia
+histogram(randn(1000); nbins=50,fillto=20)
+```
+
+![](../img/qwt_example_10.png)
+

src/Plots.jl

@@ -74,6 +74,7 @@ include("plotter.jl")
 
 # ---------------------------------------------------------
 
+include("utils.jl")
 include("args.jl")
 include("plot.jl")
 

src/gadfly.jl

@@ -30,12 +30,12 @@ function plot(pkg::GadflyPackage; kw...)
   Plot(plt, pkg, 0)
 end
 
-function getGeomFromLineType(linetype::Symbol)
+function getGeomFromLineType(linetype::Symbol, nbins::Int)
   linetype == :line && return Gadfly.Geom.line
   linetype == :dots && return Gadfly.Geom.point
   linetype == :bar && return Gadfly.Geom.bar
   linetype == :step && return Gadfly.Geom.step
-  linetype == :hist && return Gadfly.Geom.hist
+  linetype == :hist && return Gadfly.Geom.histogram(bincount=nbins)
   linetype == :none && return Gadfly.Geom.point  # change this? are we usually pairing no line with scatterplots?
   linetype == :sticks && return Gadfly.Geom.bar
   error("linetype $linetype not currently supported with Gadfly")
@@ -50,7 +50,7 @@ function getGeoms(linetype::Symbol, marker::Symbol, nbins::Int)
   else
 
     # for other linetypes, get the correct Geom
-    push!(geoms, getGeomFromLineType(linetype))
+    push!(geoms, getGeomFromLineType(linetype, nbins))
 
     # for any marker, add Geom.point
     if marker != :none
@@ -96,7 +96,7 @@ function plot!(::GadflyPackage, plt::Plot; kw...)
   end
 
   # add the layer to the Gadfly.Plot
-  append!(plt.o.layers, Gadfly.layer(unique(gfargs)...; x = x, y = d[:y]))
+  prepend!(plt.o.layers, Gadfly.layer(unique(gfargs)...; x = x, y = d[:y]))
   plt
 end
 

src/qwt.jl

@@ -3,26 +3,31 @@
 
 immutable QwtPackage <: PlottingPackage end
 
-function adjustQwtKeywords(; kw...)
+function adjustQwtKeywords(iscreating::Bool; kw...)
   d = Dict(kw)
+  d[:heatmap_n] = d[:nbins]
+
   if d[:linetype] == :hexbin
     d[:linetype] = :heatmap
   elseif d[:linetype] == :dots
     d[:linetype] = :none
     d[:marker] = :hexagon
+  elseif !iscreating && d[:linetype] == :bar
+    return barHack(; kw...)
+  elseif !iscreating && d[:linetype] == :hist
+    return barHack(; histogramHack(; kw...)...)
   end
-  d[:heatmap_n] = d[:nbins]
   d
 end
 
 function plot(pkg::QwtPackage; kw...)
-  kw = adjustQwtKeywords(;kw...)
+  kw = adjustQwtKeywords(true; kw...)
   plt = Plot(Qwt.plot(zeros(0,0); kw..., show=false), pkg, 0)
   plt
 end
 
 function plot!(::QwtPackage, plt::Plot; kw...)
-  kw = adjustQwtKeywords(;kw...)
+  kw = adjustQwtKeywords(false; kw...)
   Qwt.oplot(plt.o; kw...)
 end
 

src/utils.jl

@@ -0,0 +1,71 @@
+
+calcMidpoints(edges::AbstractVector) = Float64[0.5 * (edges[i] + edges[i+1]) for i in 1:length(edges)-1]
+
+doc"Make histogram-like bins of data"
+function binData(data, nbins)
+  lo, hi = extrema(data)
+  edges = collect(linspace(lo, hi, nbins+1))
+  midpoints = calcMidpoints(edges)
+  buckets = Int[max(2, min(searchsortedfirst(edges, x), length(edges)))-1 for x in data]
+  counts = zeros(Int, length(midpoints))
+  for b in buckets
+    counts[b] += 1
+  end
+  edges, midpoints, buckets, counts
+end
+
+doc"""
+A hacky replacement for a histogram when the backend doesn't support histograms directly.
+Convert it into a bar chart with the appropriate x/y values.
+"""
+function histogramHack(; kw...)
+  d = Dict(kw)
+
+  # we assume that the y kwarg is set with the data to be binned, and nbins is also defined
+  edges, midpoints, buckets, counts = binData(d[:y], d[:nbins])
+  d[:x] = midpoints
+  d[:y] = float(counts)
+  d[:linetype] = :bar
+  d[:fillto] = d[:fillto] == nothing ? 0.0 : d[:fillto]
+  d
+end
+
+doc"""
+A hacky replacement for a bar graph when the backend doesn't support bars directly.
+Convert it into a line chart with fillto set.
+"""
+function barHack(; kw...)
+  d = Dict(kw)
+  midpoints = d[:x]
+  heights = d[:y]
+  fillto = d[:fillto] == nothing ? 0.0 : d[:fillto]
+
+  # estimate the edges
+  dists = diff(midpoints) * 0.5
+  edges = zeros(length(midpoints)+1)
+  for i in 1:length(edges)
+    if i == 1
+      edge = midpoints[1] - dists[1]
+    elseif i == length(edges)
+      edge = midpoints[i-1] + dists[i-2]
+    else
+      edge = midpoints[i-1] + dists[i-1]
+    end
+    edges[i] = edge
+  end
+
+  x = Float64[]
+  y = Float64[]
+  for i in 1:length(heights)
+    e1, e2 = edges[i:i+1]
+    append!(x, [e1, e1, e2, e2])
+    append!(y, [fillto, heights[i], heights[i], fillto])
+  end
+
+  d[:x] = x
+  d[:y] = y
+  d[:linetype] = :line
+  d[:fillto] = fillto
+  d
+end
+