From 49dce72b0840a5bbf2840f9ca20255325e9d8c8b Mon Sep 17 00:00:00 2001
From: Anya <anyazhang01@yahoo.com>
Date: Fri, 28 Jun 2019 12:11:01 +0200
Subject: [PATCH 1/2] Calculate same-layer crossings

---
 lib/order/cross-count.js | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/lib/order/cross-count.js b/lib/order/cross-count.js
index 2f8b6b0f..18a78882 100644
--- a/lib/order/cross-count.js
+++ b/lib/order/cross-count.js
@@ -22,8 +22,34 @@ module.exports = crossCount;
  */
 function crossCount(g, layering) {
   var cc = 0;
-  for (var i = 1; i < layering.length; ++i) {
-    cc += twoLayerCrossCount(g, layering[i-1], layering[i]);
+  for (var i = 0; i < layering.length; ++i) {
+    cc += singleLayerCrossCount(g, layering[i]);
+    if (i > 0) {
+      cc += twoLayerCrossCount(g, layering[i-1], layering[i]);
+    }
+  }
+  return cc;
+}
+
+function singleLayerCrossCount(g, layer) {
+  var cc = 0;
+  if (layer.length) {
+    var layerRank = g.node(layer[0]).rank;
+    var layerIndex = _.zipObject(
+      layer,
+       _.map(layer, function (v, i) { return i; })
+    );
+
+    _.forEach(layer, function(n, i) {
+      _.forEach(g.inEdges(n), function(e) {
+        if (g.node(e.v).rank == layerRank) {
+          var otherPos = layerIndex[e.v];
+          if (Math.abs(otherPos - i) > 1) {
+            cc++;
+          }
+        }
+      });
+    });
   }
   return cc;
 }

From d48c680f74ef12d40808a101347ccd80b75ae860 Mon Sep 17 00:00:00 2001
From: Anya <anyazhang01@yahoo.com>
Date: Mon, 1 Jul 2019 12:11:10 +0200
Subject: [PATCH 2/2] Added nodes and single layer test to cross count tests

---
 test/order/cross-count-test.js | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/test/order/cross-count-test.js b/test/order/cross-count-test.js
index a884582e..c48a0c67 100644
--- a/test/order/cross-count-test.js
+++ b/test/order/cross-count-test.js
@@ -1,6 +1,8 @@
 var expect = require("../chai").expect;
 var Graph = require("../../lib/graphlib").Graph;
 var crossCount = require("../../lib/order/cross-count");
+var _ = require("lodash");
+
 
 describe("crossCount", function() {
   var g;
@@ -8,6 +10,9 @@ describe("crossCount", function() {
   beforeEach(function() {
     g = new Graph()
       .setDefaultEdgeLabel(function() { return { weight: 1 }; });
+      _.forEach(["a1", "a2", "a3"], function(v) { g.setNode(v, { rank: 1 }); });
+      _.forEach(["b1", "b2"], function(v) { g.setNode(v, { rank: 2 }); });
+      _.forEach(["c1", "c2"], function(v) { g.setNode(v, { rank: 3 }); });
   });
 
   it("returns 0 for an empty layering", function() {
@@ -39,6 +44,9 @@ describe("crossCount", function() {
   });
 
   it("works for graph #1", function() {
+    _.forEach(["a", "d"], function(v) { g.setNode(v, { rank: 1 }); });
+    _.forEach(["b", "f", "e"], function(v) { g.setNode(v, { rank: 2 }); });
+    _.forEach(["c", "i"], function(v) { g.setNode(v, { rank: 3 }); });
     g.setPath(["a", "b", "c"]);
     g.setPath(["d", "e", "c"]);
     g.setPath(["a", "f", "i"]);
@@ -46,4 +54,12 @@ describe("crossCount", function() {
     expect(crossCount(g, [["a", "d"], ["b", "e", "f"], ["c", "i"]])).equals(1);
     expect(crossCount(g, [["d", "a"], ["e", "b", "f"], ["c", "i"]])).equals(0);
   });
+
+  it("handles single-layer crossings", function() {
+    g.setEdge("a1", "b1");
+    g.setEdge("a1", "a3");
+    g.setEdge("a2", "b2");
+    expect(crossCount(g, [["a1", "a2", "a3"], ["b2", "b1"]])).equals(2);
+  });
+
 });