点抽稀算法

对密集的点抽稀，保持点的均匀分布。

dis=1000;
double degToMeter = Math.PI * 6378137 / 180.0;//6378137赤道半径，一度对应赤道上的一米
int buf = (int) (dis * 1.0e7 / degToMeter);//1公里对应多少度      

List<Pos> spector = new LinkedList<Pos>();
for (int kk = 0; kk < list.size(); kk++) {
  Feature f = (Feature) list.get(kk).getData();
  int x = (int) (f.getGeometry().getCoordinate().x * 1e7);
  int y = (int) (f.getGeometry().getCoordinate().y * 1e7);
  Pos cur = new Pos(x, y);
  cur.setBuffer(buf);
  if (spector.contains(cur)) {
    fcdel.add(f);//删除点
    
  } else {
    spector.add(cur);
    fc.add(f);//保留点
  }
}      

public class Pos {
  public int x;
  public int y;

  private int buf;

  public Pos(int x, int y) {
    this.x = x;
    this.y = y;
  }

  public void setBuffer(int buf) {
    this.buf = buf;
  }

  public boolean equals(Object pt) {
    if (pt instanceof Pos)
      return (Math.abs(this.x - ((Pos) pt).x) <= buf && Math.abs(this.y
          - ((Pos) pt).y) <= buf);
    return false;
  }

  public int hashCode() {
    return Integer.valueOf(x + "" + y);
  }

}      

注意:重写equal方法。