Segment Geometry

A geometry for line segments/vectors/arrows. There is an example in the
file geom_segment.md.

doc/geom_segment.md

@@ -0,0 +1,49 @@
+---
+title: segment
+author: Mattriks
+part: Geometry
+order: 1019
+...
+Draw separate line segments/vectors/arrows.
+Note that if you want arrows, then you need to provide a `Scale` object for both axes. See example below. 
+
+# Aesthetics
+
+  * `x`: Start of line segment.
+  * `y`: Start of line segment.
+  * `xend`: End of line segment.
+  * `yend`: End of line segment.
+  * `color` (optional): Color of line segments.
+
+# Arguments
+
+  * `arrow`: Default behavior for `Geom.segment` is to draw line segments without arrows.
+  `Geom.vector()` is `Geom.segment(arrow=true)`.
+
+
+# Examples
+
+```{.julia hide="true" results="none"}
+using RDatasets
+using Gadfly
+
+Gadfly.set_default_plot_size(6.6inch, 6.6inch)
+```
+
+```julia
+seals = RDatasets.dataset("ggplot2","seals")
+seals[:Latb] = seals[:Lat] + seals[:DeltaLat]
+seals[:Longb] = seals[:Long] + seals[:DeltaLong]
+seals[:Angle] = atan2(seals[:DeltaLat], seals[:DeltaLong])
+
+coord = Coord.cartesian(xmin=-175.0, xmax=-119, ymin=29, ymax=50)
+# Geom.vector also needs scales for both axes:
+xsc  = Scale.x_continuous(minvalue=-175.0, maxvalue=-119)
+ysc  = Scale.y_continuous(minvalue=29, maxvalue=50)
+colsc = Scale.color_continuous(minvalue=-3, maxvalue=3)
+
+layer1 = layer(seals, x=:Long, y=:Lat, xend=:Longb, yend=:Latb, Geom.vector, color=:Angle)
+
+plot(layer1, xsc, ysc, colsc, coord)
+```
+

src/Gadfly.jl

@@ -1124,7 +1124,9 @@ const default_aes_scales = @compat Dict{Symbol, Dict}(
         :numerical => Dict{Symbol, Any}(:x           => Scale.x_continuous(),
                                         :xmin        => Scale.x_continuous(),
                                         :xmax        => Scale.x_continuous(),
-                                        :xintercept  => Scale.x_continuous(),
+                                        :xintercept       => Scale.x_continuous(),
+                                        :xend  => Scale.x_continuous(),
+                                        :yend  => Scale.y_continuous(),
                                         :y           => Scale.y_continuous(),
                                         :ymin        => Scale.y_continuous(),
                                         :ymax        => Scale.y_continuous(),
@@ -1145,6 +1147,8 @@ const default_aes_scales = @compat Dict{Symbol, Dict}(
                                           :xmin       => Scale.x_discrete(),
                                           :xmax       => Scale.x_discrete(),
                                           :xintercept => Scale.x_discrete(),
+                                        :xend  => Scale.x_discrete(),
+                                        :yend  => Scale.y_discrete(),
                                           :y          => Scale.y_discrete(),
                                           :ymin       => Scale.y_discrete(),
                                           :ymax       => Scale.y_discrete(),

src/aesthetics.jl

@@ -14,6 +14,8 @@ typealias NumericalAesthetic
     x,            @compat(Union{NumericalOrCategoricalAesthetic, Distribution})
     y,            @compat(Union{NumericalOrCategoricalAesthetic, Distribution})
     z,            @compat(Union{(@compat Void), Function, Matrix})
+    xend,         NumericalAesthetic
+    yend,         NumericalAesthetic
     size,         Maybe(Vector{Measure})
     shape,        CategoricalAesthetic
     color,        Maybe(@compat(Union{AbstractVector{RGBA{Float32}},

src/data.jl

@@ -5,6 +5,8 @@
     x
     y
     z
+    xend
+    yend
     xmin
     xmax
     ymin

src/geom/segment.jl

@@ -0,0 +1,117 @@
+
+abstract SegmentGeometry <: Gadfly.GeometryElement
+
+# Geometry for vectors/arrows/segments
+immutable SegmentGeom <: SegmentGeometry 
+
+     arrow::Bool
+     filled::Bool
+     tag::Symbol 
+
+    function SegmentGeom(;arrow=false, filled=false, tag=empty_tag) 
+         new(arrow, filled, tag) 
+     end 
+end 
+
+const segment = SegmentGeom
+
+# Leave this as a function, pending extra arguments e.g. arrow attributes
+function vector(;filled::Bool=false, tag::Symbol=empty_tag)
+    return SegmentGeom(arrow=true, filled=filled, tag=tag)
+end
+
+
+function element_aesthetics(::SegmentGeom) 
+    return [:x, :y, :xend, :yend, :color] 
+end 
+
+
+function Gadfly.render(geom::SegmentGeom, theme::Gadfly.Theme, aes::Gadfly.Aesthetics,
+                subplot_layer_aess::@compat(Union{(@compat Void), Vector{Gadfly.Aesthetics}}),
+                subplot_layer_datas::@compat(Union{(@compat Void), Vector{Gadfly.Data}}),
+    scales::Dict{Symbol, Gadfly.ScaleElement})
+    render(geom, theme, aes, scales)
+end
+
+
+
+
+
+function render(geom::SegmentGeom, theme::Gadfly.Theme, aes::Gadfly.Aesthetics,
+    scales::Dict{Symbol, Gadfly.ScaleElement})
+
+    Gadfly.assert_aesthetics_defined("Geom.segment", aes, :x, :y, :xend, :yend)
+
+    function arrow{T<:Real}(x::T, y::T, xmax::T, ymax::T, xyrange::Vector{T})
+        dx = xmax-x
+        dy = ymax-y
+        vl = 0.225*hypot(dy/xyrange[2], dx/xyrange[1])
+        θ =  atan2(dy/xyrange[2], dx/xyrange[1])
+        ϕ = pi/15
+        xr = -vl*xyrange[1]*[cos(θ+ϕ), cos(θ-ϕ)]
+        yr = -vl*xyrange[2]*[sin(θ+ϕ), sin(θ-ϕ)]
+        arr = [(xmax+xr[1],ymax+yr[1]), (xmax,ymax), (xmax+xr[2],ymax+yr[2]) ]
+        return arr
+    end
+
+    n = length(aes.x)
+    color = ColorTypes.RGBA{Float32}(theme.default_color)
+    default_aes = Gadfly.Aesthetics()  
+    default_aes.color = DataArrays.DataArray(fill(color,n))
+
+    aes = inherit(aes, default_aes) 
+
+#    line_style = Gadfly.get_stroke_vector(theme.line_style)
+    line_style = theme.line_style 
+    if is(line_style, nothing)
+        line_style = [] 
+    end
+
+
+# Geom.vector requires information about scales
+
+if geom.arrow
+    xscale = scales[:x]
+    yscale = scales[:y]
+    check = [xscale.minvalue, xscale.maxvalue, yscale.minvalue, yscale.maxvalue]
+    if any( map(x -> is(x,nothing), check) )
+        error("For Geom.vector, Scale minvalue and maxvalue must be manually provided for both axes")
+    end
+    fx = xscale.trans.f
+    fy = yscale.trans.f
+    xyrange = [fx(xscale.maxvalue)-fx(xscale.minvalue),
+        fy(yscale.maxvalue)-fy(yscale.minvalue)]
+
+     arrows = [ arrow(x, y, xend, yend, xyrange)
+            for (x, y, xend, yend) in zip(aes.x, aes.y, aes.xend, aes.yend) ]
+
+end
+
+
+    segments = [ [(x,y), (xend,yend)]
+        for (x, y, xend, yend) in zip(aes.x, aes.y, aes.xend, aes.yend) ]  
+
+    classes = [string("geometry ", svg_color_class_from_label( aes.color_label([c])[1] ))
+        for c in aes.color ]
+
+    ctx = context()
+
+    compose!( ctx, Compose.line(segments, geom.tag), stroke(aes.color), linewidth(theme.line_width), 
+        strokedash(line_style), svgclass( classes )  )
+    if geom.arrow
+        if geom.filled
+            compose!(ctx, (context(), Compose.polygon(arrows), fill(aes.color), strokedash([])) )
+        else
+            compose!(ctx, (context(), Compose.line(arrows), stroke(aes.color), linewidth(theme.line_width), 
+            strokedash([]))  )        
+        end
+    end
+
+
+    return ctx
+end
+
+
+
+
+

src/geometry.jl

@@ -70,5 +70,6 @@ include("geom/ribbon.jl")
 include("geom/violin.jl")
 include("geom/polygon.jl")
 include("geom/beeswarm.jl")
+include("geom/segment.jl")
 
 end # module Geom

src/scale.jl

@@ -162,10 +162,10 @@ function make_labeler(scale::ContinuousScale)
 end
 
 
-const x_vars = [:x, :xmin, :xmax, :xintercept, :xviewmin, :xviewmax]
+const x_vars = [:x, :xmin, :xmax, :xintercept, :xviewmin, :xviewmax, :xend]
 const y_vars = [:y, :ymin, :ymax, :yintercept, :middle,
                 :upper_fence, :lower_fence, :upper_hinge, :lower_hinge,
-                :yviewmin, :yviewmax]
+    :yviewmin, :yviewmax, :yend]
 
 function continuous_scale_partial(vars::Vector{Symbol},
                                   trans::ContinuousScaleTransform)

test/runtests.jl

@@ -107,7 +107,8 @@ tests = [
     ("rug",                                   6inch, 3inch),
     ("beeswarm",                              6inch, 3inch),
     ("issue871",                              6inch, 3inch),
-    ("issue882",                              6inch, 3inch)
+    ("issue882",                              6inch, 3inch),
+    ("vector",                                3.3inch, 3.3inch)
 ]
 
 

test/vector.jl

@@ -0,0 +1,14 @@
+
+
+using DataFrames, Gadfly
+
+
+srand(123)
+D = convert(DataFrame, 99*rand(4, 4)+0.5)
+
+xsc  = Scale.x_continuous(minvalue=0.0, maxvalue=100)
+ysc  = Scale.y_continuous(minvalue=0.0, maxvalue=100)
+
+plot(D, x=:x1, y=:x2, xend=:x3, yend=:x4, Geom.segment(arrow=true), xsc, ysc)
+plot(D, x=:x1, y=:x2, xend=:x3, yend=:x4, Geom.vector, xsc, ysc)
+