Merge pull request #126 from pkofod/dev

Add abline! which creates a straight line according to the formula b+…

src/Plots.jl

@@ -59,6 +59,7 @@ export
   path3d!,
   scatter3d,
   scatter3d!,
+  abline!,
 
   title!,
   xlabel!,

src/recipes.jl

@@ -130,3 +130,9 @@ function spy{T<:Real}(y::AMat{T}; kw...)
   heatmap(J, I; leg=false, yflip=true, nbins=size(y), kw...)
 end
 
+"Adds a+bx... straight line over the current plot"
+function abline!(plt::Plot, a, b; kw...)
+    plot!(plt, [extrema(plt)...], x -> b + a*x; kw...)
+end
+
+abline!(args...; kw...) = abline!(current(), args...; kw...)

src/utils.jl

@@ -465,3 +465,11 @@ mm2inch(mm::Real) = float(mm / MM_PER_INCH)
 px2mm(px::Real) = float(px * MM_PER_PX)
 mm2px(mm::Real) = float(px / MM_PER_PX)
 
+
+"Smallest x in plot"
+xmin(plt::Plot) = minimum([minimum(d[:x]) for d in plt.seriesargs])
+"Largest x in plot"
+xmax(plt::Plot) = maximum([maximum(d[:x]) for d in plt.seriesargs])
+
+"Extrema of x-values in plot"
+Base.extrema(plt::Plot) = (xmin(plt), xmax(plt))