FilteredConvexHull2D (ELKI: Environment for DeveLoping KDD-Applications Supported by Index-Structures)

java.lang.Object
- de.lmu.ifi.dbs.elki.math.geometry.FilteredConvexHull2D

```
public class FilteredConvexHull2D
extends java.lang.Object
```
Accelerate computing the convex hull with a simple filter. For this filter, we maintain a simple box that is guaranteed to be fully inside the convex hull. Points in this rectangle will be skipped. TODO: allow using this with other bounding box agorithms, too.

Since:

0.7.5

Author:

Erich Schubert

Field Summary

Fields
Modifier and Type	Field and Description
`private double[]`	`bottomleft` Top-left point
`private double[]`	`bottomright` Top-left point
`private double`	`bottomy` Left bound
`private double`	`leftx` Left bound
`private java.util.List<double[]>`	`points` The current set of candidate points.
`private Polygon`	`poly` Computed polygon.
`private double`	`rightx` Left bound
`private double[]`	`topleft` Top-left point
`private double[]`	`topright` Top-left point
`private double`	`topy` Left bound

Constructor Summary

Constructors
Constructor and Description

FilteredConvexHull2D()
Constructor.

Constructors
Constructor and Description
`FilteredConvexHull2D()` Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`add(double... point)` Add a single point to the list (this does not compute the hull!)
`private boolean`	`checkCandidate(double[] point)`
`private boolean`	`checkCandidateUpdate(double[] point)` Check whether a point is inside the current bounds, and update the bounds
`private Polygon`	`computeConvexHull()` Compute the convex hull.
`Polygon`	`getHull()` Compute the convex hull, and return the resulting polygon.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - points
```
private java.util.List<double[]> points
```
    The current set of candidate points.
  - leftx
```
private double leftx
```
    Left bound
  - rightx
```
private double rightx
```
    Left bound
  - topy
```
private double topy
```
    Left bound
  - bottomy
```
private double bottomy
```
    Left bound
  - topleft
```
private double[] topleft
```
    Top-left point
  - topright
```
private double[] topright
```
    Top-left point
  - bottomright
```
private double[] bottomright
```
    Top-left point
  - bottomleft
```
private double[] bottomleft
```
    Top-left point
  - poly
```
private Polygon poly
```
    Computed polygon.
- Constructor Detail
  - FilteredConvexHull2D
```
public FilteredConvexHull2D()
```
    Constructor.
- Method Detail
  - add
```
public void add(double... point)
```
    Add a single point to the list (this does not compute the hull!)
    
    Parameters:
    
    point - Point to add
  - computeConvexHull
```
private Polygon computeConvexHull()
```
    Compute the convex hull.
    
    Returns:
    
    resulting polygon
  - checkCandidate
```
private boolean checkCandidate(double[] point)
```
  - checkCandidateUpdate
```
private boolean checkCandidateUpdate(double[] point)
```
    Check whether a point is inside the current bounds, and update the bounds
    
    Parameters:
    
    point - New point
    
    Returns:
    
    true if the point is potentially on the hull
  - getHull
```
public Polygon getHull()
```
    Compute the convex hull, and return the resulting polygon.
    
    Returns:
    
    Polygon of the hull

Class FilteredConvexHull2D

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

points

leftx

rightx

topy

bottomy

topleft

topright

bottomright

bottomleft

poly

Constructor Detail

FilteredConvexHull2D

Method Detail

add

computeConvexHull

checkCandidate

checkCandidateUpdate

getHull