From 567ba507f485300e7f1f8cfd387533a9c5bc1e86 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Ra=C3=BAl=20Mar=C3=ADn=20Rodr=C3=ADguez?=
 <rmrodriguez@carto.com>
Date: Mon, 1 Oct 2018 15:57:42 +0000
Subject: [PATCH] Avoid division by zero in kmeans

Closes #4188
Closes https://github.com/postgis/postgis/pull/309


git-svn-id: http://svn.osgeo.org/postgis/trunk@16860 b70326c6-7e19-0410-871a-916f4a2858ee
---
 NEWS                 | 1 +
 liblwgeom/lwkmeans.c | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index 8e5c6c41b..7423db1f3 100644
--- a/NEWS
+++ b/NEWS
@@ -20,6 +20,7 @@ PostGIS 3.0.0
   - #4176, ST_Intersects supports GEOMETRYCOLLECTION (Darafei Praliaskouski)
   - #4181, St_AsMVTGeom: Avoid type changes due to validation (Raúl Marín)
   - #4183, St_AsMVTGeom: Drop invalid geometries after simplification (Raúl Marín)
+  - #4188, Avoid division by zero in kmeans (Raúl Marín)
 
 PostGIS 2.5.0
 2018/09/23
diff --git a/liblwgeom/lwkmeans.c b/liblwgeom/lwkmeans.c
index 360983daf..8a4931add 100644
--- a/liblwgeom/lwkmeans.c
+++ b/liblwgeom/lwkmeans.c
@@ -82,8 +82,11 @@ update_means(POINT2D** objs, int* clusters, uint32_t n, POINT2D** centers, uint3
 	}
 	for (i = 0; i < k; i++)
 	{
-		centers[i]->x /= weights[i];
-		centers[i]->y /= weights[i];
+		if (weights[i])
+		{
+			centers[i]->x /= weights[i];
+			centers[i]->y /= weights[i];
+		}
 	}
 }
 
-- 
2.40.0