Class AklToussaintHeuristic
- java.lang.Object
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- org.apache.commons.math3.geometry.euclidean.twod.hull.AklToussaintHeuristic
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public final class AklToussaintHeuristic extends java.lang.Object
A simple heuristic to improve the performance of convex hull algorithms.The heuristic is based on the idea of a convex quadrilateral, which is formed by four points with the lowest and highest x / y coordinates. Any point that lies inside this quadrilateral can not be part of the convex hull and can thus be safely discarded before generating the convex hull itself.
The complexity of the operation is O(n), and may greatly improve the time it takes to construct the convex hull afterwards, depending on the point distribution.
- Since:
- 3.3
- See Also:
- Akl-Toussaint heuristic (Wikipedia)
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Constructor Summary
Constructors Modifier Constructor Description private
AklToussaintHeuristic()
Hide utility constructor.
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description private static java.util.List<Vector2D>
buildQuadrilateral(Vector2D... points)
Build the convex quadrilateral with the found corner points (with min/max x/y coordinates).private static boolean
insideQuadrilateral(Vector2D point, java.util.List<Vector2D> quadrilateralPoints)
Checks if the given point is located within the convex quadrilateral.static java.util.Collection<Vector2D>
reducePoints(java.util.Collection<Vector2D> points)
Returns a point set that is reduced by all points for which it is safe to assume that they are not part of the convex hull.
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Method Detail
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reducePoints
public static java.util.Collection<Vector2D> reducePoints(java.util.Collection<Vector2D> points)
Returns a point set that is reduced by all points for which it is safe to assume that they are not part of the convex hull.- Parameters:
points
- the original point set- Returns:
- a reduced point set, useful as input for convex hull algorithms
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buildQuadrilateral
private static java.util.List<Vector2D> buildQuadrilateral(Vector2D... points)
Build the convex quadrilateral with the found corner points (with min/max x/y coordinates).- Parameters:
points
- the respective points with min/max x/y coordinate- Returns:
- the quadrilateral
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insideQuadrilateral
private static boolean insideQuadrilateral(Vector2D point, java.util.List<Vector2D> quadrilateralPoints)
Checks if the given point is located within the convex quadrilateral.- Parameters:
point
- the point to checkquadrilateralPoints
- the convex quadrilateral, represented by 4 points- Returns:
true
if the point is inside the quadrilateral,false
otherwise
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