private Node BBFFindNearest(Node tree, Train target)
{
Node nearest = new Node(); //最近邻节点
nearest = tree;
float priority = -1; //优先级
//计算优先级
priority = this.CalPriority(nearest, target, tree.split);
this.InsertPriorityList(nearest, priority); //将根节点加入优先队列中
Node topNode = null; //优先级最高的节点
Node currentNode = null;
double dist = 0;
while (priorityList.Count > 0)
{
topNode = priorityList[0].node; //优先队列中的第一个总是优先级最高的
this.RmovePriority(topNode);
while (topNode != null)
{
//当前节点不是叶子节点
if (topNode.leftNode != null || topNode.righNode != null)
{
int split = topNode.split;
if (split == 0)
{
if (target.positionX <= topNode.point.positionX)
{
//current = topNode.point;
//若右节点不为空，将右子树节点添加到优先队列中
if (topNode.righNode != null)
{
priority = this.CalPriority(topNode.righNode, target, split);
this.InsertPriorityList(topNode.righNode, priority);
}
topNode = topNode.leftNode;
}
else
{
//current = topNode.point;
//将左子树节点添加到优先级队列中
if (topNode.leftNode != null)
{
priority = this.CalPriority(topNode.leftNode, target, split);
this.InsertPriorityList(topNode.leftNode, priority);
}
topNode = topNode.righNode;
}
currentNode = topNode;
}
else if (split == 1)
{
if (target.positionY <= topNode.point.positionY)
{
//current = topNode.point;
//将右子树节点添加到优先队列中
if (topNode.righNode != null)
{
priority = this.CalPriority(topNode.righNode, target, split);
this.InsertPriorityList(topNode.righNode, priority);
}
topNode = topNode.leftNode;
}
else
{
//current = topNode.point;
//将左子树节点添加到优先级队列中
if (topNode.leftNode != null)
{
priority = this.CalPriority(topNode.leftNode, target, split);
this.InsertPriorityList(topNode.leftNode, priority);
}
topNode = topNode.righNode;
}
currentNode = topNode;
}
else
{
if (target.positionZ <= topNode.point.positionZ)
{
//current = topNode.point;
//将右子树节点添加到优先队列中
if (topNode.righNode != null)
{
priority = this.CalPriority(topNode.righNode, target, split);
this.InsertPriorityList(topNode.righNode, priority);
}
topNode = topNode.leftNode;
}
else
{
//current = topNode.point;
//将左子树节点添加到优先级队列中
if (topNode.leftNode != null)
{
priority = this.CalPriority(topNode.leftNode, target, split);
this.InsertPriorityList(topNode.leftNode, priority);
}
topNode = topNode.righNode;
}
currentNode = topNode;
}
}
else
{
currentNode = topNode;
topNode = null; //叶子节点
}
if (currentNode != null && Distance(nearest.point, target) > Distance(currentNode.point, target))
{
nearest = currentNode;
dist = Distance(currentNode.point, target);
}
}
}
return(nearest);
}
//寻找K个近邻的节点
private void BBFKNNFind(Node tree, Train target, int k = 3)
{
}
private Node KDTreeFindNearest(Node tree, Train target)
{
double dist = double.MaxValue; //最近邻和目标点之间的距离
Node nearest = null; //最近邻节点
Node searchNode = tree; //根节点
List <Node> searchPath = new List <Node>(); //搜索路径
#region 检索搜索路径
while (searchNode != null)
{
searchPath.Add(searchNode); //添加当前搜索节点
if (searchNode.split == 0)
{
//X方向轴分割
if (target.positionX <= searchNode.point.positionX)
{
searchNode = searchNode.leftNode;
}
else
{
searchNode = searchNode.righNode;
}
}
else if (searchNode.split == 1)
{
//Y方向轴分割
if (target.positionY <= searchNode.point.positionY)
{
searchNode = searchNode.leftNode;
}
else
{
searchNode = searchNode.righNode;
}
}
else
{
if (target.positionZ <= searchNode.point.positionZ)
{
searchNode = searchNode.leftNode;
}
else
{
searchNode = searchNode.righNode;
}
}
}
#endregion
nearest = searchPath[searchPath.Count - 1]; //获取搜索路径最后一个节点
searchPath.Remove(nearest); //从搜索路径中删除假定的最近邻节点
//计算两个节点之间的距离
dist = this.Distance(nearest.point, target);
#region 回溯路径搜索
Node backNode;
int split = -1;
while (searchPath.Count > 0)
{
backNode = searchPath[searchPath.Count - 1]; //取搜索路径最后一个
if (backNode.leftNode == null && backNode.righNode == null)
{
//该节点为叶子节点
if (Distance(nearest.point, target) > Distance(backNode.point, target))
{
nearest = backNode;
dist = Distance(backNode.point, target);
}
}
else
{
split = backNode.split; //取出当前的分割方向轴
if (split == 0)
{
if (Distance(backNode.point, target) < dist)
{
nearest = backNode;
dist = Distance(backNode.point, target);
}
//确定是否进入子空间搜索
float disTmp = Math.Abs(target.positionX - backNode.point.positionX);
if (disTmp < dist)
{
//判断目标点是在左子空间还是右子空间
if (target.positionX > backNode.point.positionX)
{
//目标点在右子空间，则需要进入左子空间进行搜索
searchNode = backNode.leftNode;
}
else
{
searchNode = backNode.righNode;
}
searchPath.Add(searchNode); //添加搜索节点
}
}
else if (split == 1)
{
if (Distance(backNode.point, target) < dist)
{
nearest = backNode;
dist = Distance(backNode.point, target);
}
//确定是否进入子空间搜索
float disTmp = Math.Abs(target.positionY - backNode.point.positionY);
if (disTmp < dist)
{
//判断目标点是在左子空间还是右子空间
if (target.positionY > backNode.point.positionY)
{
//目标点在右子空间，则需要进入左子空间进行搜索
searchNode = backNode.leftNode;
}
else
{
searchNode = backNode.righNode;
}
searchPath.Add(searchNode); //添加搜索节点
}
}
else
{
if (Distance(backNode.point, target) < dist)
{
nearest = backNode;
dist = Distance(backNode.point, target);
}
//确定是否进入子空间搜索
float disTmp = Math.Abs(target.positionZ - backNode.point.positionZ);
if (disTmp < dist)
{
//判断目标点是在左子空间还是右子空间
if (target.positionZ > backNode.point.positionZ)
{
//目标点在右子空间，则需要进入左子空间进行搜索
searchNode = backNode.leftNode;
}
else
{
searchNode = backNode.righNode;
}
searchPath.Add(searchNode); //添加搜索节点
}
}
}
searchPath.Remove(backNode);
}
#endregion
return(nearest); //返回最近邻节点
}