Module math
Package de.lmu.ifi.dbs.elki.data.spatial

Class Polygon

java.lang.Object
de.lmu.ifi.dbs.elki.data.spatial.Polygon
All Implemented Interfaces:
SpatialComparable
public class Polygon extends Object implements SpatialComparable
Class representing a simple polygon. While you can obviously store non-simple polygons in this, note that many of the supplied methods will assume that the polygons are simple.
Author:
Erich Schubert

  • Constructor Details

    • Polygon

      public Polygon(List<Vector> points)
      Constructor.
      Parameters:
      points - Polygon points

    • Polygon

      public Polygon(List<Vector> points, double minx, double maxx, double miny, double maxy)

  • Method Details

    • iter

      public ArrayListIter<Vector> iter()
      Get an iterator to the vector contents.
      Returns:
      Iterator

    • appendToBuffer

      public void appendToBuffer(StringBuilder buf)
      Append the polygon to the buffer.
      Parameters:
      buf - Buffer to append to

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • size

      public int size()
      Get the polygon length.
      Returns:
      Polygon length

    • get

      public Vector get(int idx)
      Get a vector by index.
      Parameters:
      idx - Index to get
      Returns:
      Vector

    • getDimensionality

      public int getDimensionality()
      Description copied from interface: SpatialComparable
      Returns the dimensionality of the object.
      Specified by:
      getDimensionality in interface SpatialComparable
      Returns:
      the dimensionality

    • getMin

      public double getMin(int dimension)
      Description copied from interface: SpatialComparable
      Returns the minimum coordinate at the specified dimension.
      Specified by:
      getMin in interface SpatialComparable
      Parameters:
      dimension - the dimension for which the coordinate should be returned, where 0 ≤ dimension < getDimensionality()
      Returns:
      the minimum coordinate at the specified dimension

    • getMax

      public double getMax(int dimension)
      Description copied from interface: SpatialComparable
      Returns the maximum coordinate at the specified dimension.
      Specified by:
      getMax in interface SpatialComparable
      Parameters:
      dimension - the dimension for which the coordinate should be returned, where 0 ≤ dimension < getDimensionality()
      Returns:
      the maximum coordinate at the specified dimension

    • testClockwise

      public int testClockwise()
      Test polygon orientation.
      Returns:
      -1, 0, 1 for counterclockwise, undefined and clockwise.

    • intersects2DIncomplete

      public boolean intersects2DIncomplete(Polygon other)
      Simple polygon intersection test.

      FIXME: while this is found on some web pages as "solution" and satisfies or needs, it clearly is not correct; not even for convex polygons: Consider a cross where the two bars are made out of four vertices each. No vertex is inside the other polygon, yet they intersect. I knew this before writing this code, but this O(n) code was the simplest thing to come up with, and it would work for our current data sets. A way to fix this is to augment it with the obvious O(n*n) segment intersection test. (Note that you will still need to test for point containment, since the whole polygon could be contained in the other!)

      Parameters:
      other - Other polygon
      Returns:
      True when the polygons intersect

    • containsPoint2D

      public boolean containsPoint2D(Vector v)
      Point in polygon test, based on http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html by W. Randolph Franklin
      Parameters:
      v - Point to test
      Returns:
      True when contained.