From 04b13ab276ab7cccc3bb7688aa89ce3d011af106 Mon Sep 17 00:00:00 2001
From: chris-stone <chris-stone@outlook.com>
Date: Fri, 21 Mar 2014 14:15:50 -0600
Subject: [PATCH] Source link sorting by angle

Incoming source links to a node are sorted by the angle between the
source and target nodes, rather than their difference in y. It produces
cleaner diagrams, and has a customizable weighting factor to give more
weight to the x difference between nodes. The default value of 3 seems
to work well.
---
 sankey/sankey.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sankey/sankey.js b/sankey/sankey.js
index c3bc59f..a5c5f1a 100644
--- a/sankey/sankey.js
+++ b/sankey/sankey.js
@@ -4,7 +4,8 @@ d3.sankey = function() {
       nodePadding = 8,
       size = [1, 1],
       nodes = [],
-      links = [];
+      links = [],
+      sourceDepthSortWeight = 3;
 
   sankey.nodeWidth = function(_) {
     if (!arguments.length) return nodeWidth;
@@ -272,7 +273,7 @@ d3.sankey = function() {
     });
 
     function ascendingSourceDepth(a, b) {
-      return a.source.y - b.source.y;
+       return -(Math.atan((a.target.y - a.source.y) / Math.pow(a.target.x - a.source.x, sourceDepthSortWeight)) - Math.atan((b.target.y - b.source.y) / Math.pow(b.target.x - b.source.x, sourceDepthSortWeight)));
     }
 
     function ascendingTargetDepth(a, b) {