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Posted to issues@commons.apache.org by "Thomas Neidhart (JIRA)" <ji...@apache.org> on 2014/07/10 23:42:04 UTC
[jira] [Resolved] (MATH-1135) Bug in MonotoneChain: a collinear
point landing on the existing boundary should be dropped (patch)
[ https://issues.apache.org/jira/browse/MATH-1135?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Thomas Neidhart resolved MATH-1135.
-----------------------------------
Resolution: Fixed
Fix Version/s: 3.4
Fixed in r1609577.
> Bug in MonotoneChain: a collinear point landing on the existing boundary should be dropped (patch)
> --------------------------------------------------------------------------------------------------
>
> Key: MATH-1135
> URL: https://issues.apache.org/jira/browse/MATH-1135
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.3
> Reporter: Guillaume Marceau
> Priority: Minor
> Labels: patch
> Fix For: 3.4
>
> Attachments: MonotoneChain_testCollinnearPointOnExistingBoundary.patch
>
>
> The is a bug on the code in MonotoneChain.java that attempts to handle the case of a point on the line formed by the previous last points and the last point of the chain being constructed. When `includeCollinearPoints` is false, the point should be dropped entirely. In common-math 3,3, the point is added, which in some cases can cause a `ConvergenceException` to be thrown.
> In the patch below, the data points are from a case that showed up in testing before we went to production.
> {code:java}
> Index: src/main/java/org/apache/commons/math3/geometry/euclidean/twod/hull/MonotoneChain.java
> ===================================================================
> --- src/main/java/org/apache/commons/math3/geometry/euclidean/twod/hull/MonotoneChain.java (revision 1609491)
> +++ src/main/java/org/apache/commons/math3/geometry/euclidean/twod/hull/MonotoneChain.java (working copy)
> @@ -160,8 +160,8 @@
> } else {
> if (distanceToCurrent > distanceToLast) {
> hull.remove(size - 1);
> + hull.add(point);
> }
> - hull.add(point);
> }
> return;
> } else if (offset > 0) {
> Index: src/test/java/org/apache/commons/math3/geometry/euclidean/twod/hull/ConvexHullGenerator2DAbstractTest.java
> ===================================================================
> --- src/test/java/org/apache/commons/math3/geometry/euclidean/twod/hull/ConvexHullGenerator2DAbstractTest.java (revision 1609491)
> +++ src/test/java/org/apache/commons/math3/geometry/euclidean/twod/hull/ConvexHullGenerator2DAbstractTest.java (working copy)
> @@ -204,6 +204,24 @@
> }
>
> @Test
> + public void testCollinnearPointOnExistingBoundary() {
> + final Collection<Vector2D> points = new ArrayList<Vector2D>();
> + points.add(new Vector2D(7.3152, 34.7472));
> + points.add(new Vector2D(6.400799999999997, 34.747199999999985));
> + points.add(new Vector2D(5.486399999999997, 34.7472));
> + points.add(new Vector2D(4.876799999999999, 34.7472));
> + points.add(new Vector2D(4.876799999999999, 34.1376));
> + points.add(new Vector2D(4.876799999999999, 30.48));
> + points.add(new Vector2D(6.0959999999999965, 30.48));
> + points.add(new Vector2D(6.0959999999999965, 34.1376));
> + points.add(new Vector2D(7.315199999999996, 34.1376));
> + points.add(new Vector2D(7.3152, 30.48));
> +
> + final ConvexHull2D hull = generator.generate(points);
> + checkConvexHull(points, hull);
> + }
> +
> + @Test
> public void testIssue1123() {
>
> List<Vector2D> points = new ArrayList<Vector2D>();
> {code}
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