From 8cafda35775944c84211f8daa28133428bddb169 Mon Sep 17 00:00:00 2001
From: BobLd <boris.ledeist@edhec.com>
Date: Mon, 9 Mar 2020 11:10:33 +0000
Subject: [PATCH] handle nearest neighbour not found

---
 .../ClusteringAlgorithms.cs                       |  7 +++++--
 .../KdTree.cs                                     | 15 ++++++++++++---
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/UglyToad.PdfPig.DocumentLayoutAnalysis/ClusteringAlgorithms.cs b/src/UglyToad.PdfPig.DocumentLayoutAnalysis/ClusteringAlgorithms.cs
index 58bc2d5e..072469a5 100644
--- a/src/UglyToad.PdfPig.DocumentLayoutAnalysis/ClusteringAlgorithms.cs
+++ b/src/UglyToad.PdfPig.DocumentLayoutAnalysis/ClusteringAlgorithms.cs
@@ -63,9 +63,12 @@
                 {
                     var paired = kdTree.FindNearestNeighbours(pivot, pivotPoint, distMeasure, out int index, out double dist);
 
-                    if (filterFinal(pivot, paired) && dist < maxDistanceFunction(pivot, paired))
+                    if (index != -1)
                     {
-                        indexes[e] = index;
+                        if (filterFinal(pivot, paired) && dist < maxDistanceFunction(pivot, paired))
+                        {
+                            indexes[e] = index;
+                        }
                     }
                 }
             });
diff --git a/src/UglyToad.PdfPig.DocumentLayoutAnalysis/KdTree.cs b/src/UglyToad.PdfPig.DocumentLayoutAnalysis/KdTree.cs
index 1652ea9f..50a41bdc 100644
--- a/src/UglyToad.PdfPig.DocumentLayoutAnalysis/KdTree.cs
+++ b/src/UglyToad.PdfPig.DocumentLayoutAnalysis/KdTree.cs
@@ -66,12 +66,21 @@
         }
 
         #region NN
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="pivot"></param>
+        /// <param name="pivotPointFunc"></param>
+        /// <param name="distanceMeasure"></param>
+        /// <param name="index">The nearest neighbour's index (returns -1 if not found).</param>
+        /// <param name="distance">The distance between the pivot and the nearest neighbour (returns <see cref="double.NaN"/> if not found).</param>
+        /// <returns>The nearest neighbour's element.</returns>
         public T FindNearestNeighbours(T pivot, Func<T, PdfPoint> pivotPointFunc, Func<PdfPoint, PdfPoint, double> distanceMeasure, out int index, out double distance)
         {
             var result = FindNearestNeighbours(Root, pivot, pivotPointFunc, distanceMeasure);
-            index = result.Item1.Index;
-            distance = result.Item2.Value;
-            return result.Item1.Element;
+            index = result.Item1 != null ? result.Item1.Index : -1;
+            distance = result.Item2.HasValue ? result.Item2.Value : double.NaN;
+            return result.Item1 != null ? result.Item1.Element : default;
         }
 
         private static (KdTreeNode<T>, double?) FindNearestNeighbours(KdTreeNode<T> node, T pivot, Func<T, PdfPoint> pivotPointFunc, Func<PdfPoint, PdfPoint, double> distance)