From 2d1a0c4568fcb6a1e0c57c526329e4665dfbddc7 Mon Sep 17 00:00:00 2001
From: Vitaly Lysenkov <vlysenkov@google.com>
Date: Fri, 19 Mar 2021 14:14:28 +0100
Subject: [PATCH 1/3] Optimize RadiusResultSet::copy

Perform std::partial_sort instead of full std::sort in RadiusResultSet if not all items need to be returned.
---
 src/cpp/flann/util/result_set.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/cpp/flann/util/result_set.h b/src/cpp/flann/util/result_set.h
index 90e5643c..1e7cc382 100644
--- a/src/cpp/flann/util/result_set.h
+++ b/src/cpp/flann/util/result_set.h
@@ -492,7 +492,12 @@ class RadiusResultSet : public ResultSet<DistanceType>
     	if (sorted) {
     		// std::sort_heap(dist_index_.begin(), dist_index_.end());
     		// sort seems faster here, even though dist_index_ is a heap
-    		std::sort(dist_index_.begin(), dist_index_.end());
+		std::partial_sort(
+			dist_index_.begin(),
+			num_elements<size()
+				? dist_index_.begin()+num_elements
+				: dist_index_.end(),
+			dist_index_.end());
     	}
     	else {
     		if (num_elements<size()) {

From dc4c1cc0ee7f397b3e0067a8ccd28a4e0be0e710 Mon Sep 17 00:00:00 2001
From: Vitaly Lysenkov <vlysenkov@google.com>
Date: Tue, 30 Mar 2021 16:19:03 +0200
Subject: [PATCH 2/3] Update result_set.h

Branched between sort and partial_sort; used the more explicit dist_index_.size() instead of size().
---
 src/cpp/flann/util/result_set.h | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/src/cpp/flann/util/result_set.h b/src/cpp/flann/util/result_set.h
index 1e7cc382..fe2ed12a 100644
--- a/src/cpp/flann/util/result_set.h
+++ b/src/cpp/flann/util/result_set.h
@@ -492,15 +492,14 @@ class RadiusResultSet : public ResultSet<DistanceType>
     	if (sorted) {
     		// std::sort_heap(dist_index_.begin(), dist_index_.end());
     		// sort seems faster here, even though dist_index_ is a heap
-		std::partial_sort(
-			dist_index_.begin(),
-			num_elements<size()
-				? dist_index_.begin()+num_elements
-				: dist_index_.end(),
-			dist_index_.end());
-    	}
+   			if (num_elements<dist_index_.size()) {
+    			std::partial_sort(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());
+    		} else {
+    			std::sort(dist_index_.begin(), dist_index_.end());
+				}
+			}
     	else {
-    		if (num_elements<size()) {
+    		if (num_elements<dist_index_.size()) {
     			std::nth_element(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());
     		}
     	}

From f7c007b4279fce58613650a0b89eb0f34b3202c2 Mon Sep 17 00:00:00 2001
From: Vitaly Lysenkov <vlysenkov@google.com>
Date: Tue, 30 Mar 2021 16:21:19 +0200
Subject: [PATCH 3/3] Update result_set.h

Fix formatting.
---
 src/cpp/flann/util/result_set.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/cpp/flann/util/result_set.h b/src/cpp/flann/util/result_set.h
index fe2ed12a..3e42d7c0 100644
--- a/src/cpp/flann/util/result_set.h
+++ b/src/cpp/flann/util/result_set.h
@@ -492,12 +492,12 @@ class RadiusResultSet : public ResultSet<DistanceType>
     	if (sorted) {
     		// std::sort_heap(dist_index_.begin(), dist_index_.end());
     		// sort seems faster here, even though dist_index_ is a heap
-   			if (num_elements<dist_index_.size()) {
+   		if (num_elements<dist_index_.size()) {
     			std::partial_sort(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());
     		} else {
     			std::sort(dist_index_.begin(), dist_index_.end());
-				}
-			}
+		}
+	}
     	else {
     		if (num_elements<dist_index_.size()) {
     			std::nth_element(dist_index_.begin(), dist_index_.begin()+num_elements, dist_index_.end());