[geos-commits] [SCM] GEOS branch main updated. 1ea477e8cae3e7da22ce645cf29665a9e21e8641

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- Log -----------------------------------------------------------------
commit 1ea477e8cae3e7da22ce645cf29665a9e21e8641
Author: Daniel Baston <dbaston at gmail.com>
Date:   Sat Mar 7 20:10:21 2026 -0500

    DBSCAN: Fix unassigned clusters with minPoints <= 1 (#1386)

diff --git a/src/operation/cluster/DBSCANClusterFinder.cpp b/src/operation/cluster/DBSCANClusterFinder.cpp
index 1a87eb887..15da6c012 100644
--- a/src/operation/cluster/DBSCANClusterFinder.cpp
+++ b/src/operation/cluster/DBSCANClusterFinder.cpp
@@ -44,8 +44,10 @@ Clusters DBSCANClusterFinder::process(const std::vector<const geom::Geometry*> &
                       index::strtree::TemplateSTRtree<std::size_t> & tree,
                       UnionFind & uf) {
 
-    std::vector<bool> in_a_cluster(components.size());
-    std::vector<bool> is_in_core(components.size());
+    const bool allInputsInCluster = m_minPoints <= 1;
+
+    std::vector<bool> in_a_cluster(components.size(), allInputsInCluster);
+    std::vector<bool> is_in_core(components.size(), allInputsInCluster);
 
     std::vector<size_t> hits;
     std::vector<size_t> neighbors;
@@ -59,7 +61,7 @@ Clusters DBSCANClusterFinder::process(const std::vector<const geom::Geometry*> &
         });
 
         if (hits.size() < m_minPoints) {
-            // We didn't find enough points do do anything even if they're all within eps.
+            // We didn't find enough points to do anything even if they're all within eps.
             continue;
         }
 
diff --git a/tests/unit/capi/GEOSClusterTest.cpp b/tests/unit/capi/GEOSClusterTest.cpp
index f96d91ce5..c8136720f 100644
--- a/tests/unit/capi/GEOSClusterTest.cpp
+++ b/tests/unit/capi/GEOSClusterTest.cpp
@@ -105,6 +105,8 @@ template<>
 template<>
 void object::test<2>()
 {
+    set_test_name("DBSCAN");
+
     input_ = fromWKT(
                  "GEOMETRYCOLLECTION ("
                  "POINT (0 0),"
@@ -118,6 +120,24 @@ void object::test<2>()
                  "POINT ( 3 0.1)"
                  ")");
 
+    {
+        GEOSClusterInfo* clusters = GEOSClusterDBSCAN(input_, 0.01, 0);
+        ensure_equals("nine clusters with eps=0.01, minPoints = 0", GEOSClusterInfo_getNumClusters(clusters), 9u);
+        GEOSClusterInfo_destroy(clusters);
+    }
+
+    {
+        GEOSClusterInfo* clusters = GEOSClusterDBSCAN(input_, 0.01, 1);
+        ensure_equals("nine clusters with eps=0.01, minPoints = 1", GEOSClusterInfo_getNumClusters(clusters), 9u);
+        GEOSClusterInfo_destroy(clusters);
+    }
+
+    {
+        GEOSClusterInfo* clusters = GEOSClusterDBSCAN(input_, 0.1, 1);
+        ensure_equals("five clusters with eps=0.1, minPoints = 1", GEOSClusterInfo_getNumClusters(clusters), 5u);
+        GEOSClusterInfo_destroy(clusters);
+    }
+
     {
         GEOSClusterInfo* clusters = GEOSClusterDBSCAN(input_, 1.01, 5);
         ensure_equals("two clusters with minPoints = 5", GEOSClusterInfo_getNumClusters(clusters), 2u);

-----------------------------------------------------------------------

Summary of changes:
 src/operation/cluster/DBSCANClusterFinder.cpp |  8 +++++---
 tests/unit/capi/GEOSClusterTest.cpp           | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)


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