From 3f42e9c5bd845184734dae8418b544af7d5b7954 Mon Sep 17 00:00:00 2001
From: Patrick Kofod Mogensen <patrick.mogensen@gmail.com>
Date: Tue, 2 Feb 2016 22:02:31 +0100
Subject: [PATCH] Add abline! which creates a straight line according to the
 formula b+a*x, and export abline! Also add utility functions xmin(plt::Plot)
 and xmax(plt::Plot).

---
 src/Plots.jl   | 1 +
 src/recipes.jl | 6 ++++++
 src/utils.jl   | 6 ++++++
 3 files changed, 13 insertions(+)

diff --git a/src/Plots.jl b/src/Plots.jl
index feca5ce9..5dcd596d 100644
--- a/src/Plots.jl
+++ b/src/Plots.jl
@@ -59,6 +59,7 @@ export
   path3d!,
   scatter3d,
   scatter3d!,
+  abline!,
 
   title!,
   xlabel!,
diff --git a/src/recipes.jl b/src/recipes.jl
index 44ba5d85..45309c12 100644
--- a/src/recipes.jl
+++ b/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, [xmin(plt), xmax(plt)], x -> b + a*x; kw...)
+end
+
+abline!(args...; kw...) = abline!(current(), args...; kw...)
diff --git a/src/utils.jl b/src/utils.jl
index 68f20583..bf97febd 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -465,3 +465,9 @@ 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])
+