/// <summary>
/// Insert a new point into this leaf node.
/// </summary>
/// <param name="tPoint">The position which represents the data.</param>
/// <param name="kValue">The value of the data.</param>
public void AddPoint(double[] tPoint, T kValue)
{
// Find the correct leaf node.
KDNode_Rednaxela <T> pCursor = this;
while (!pCursor.IsLeaf)
{
// Extend the size of the leaf.
pCursor.ExtendBounds(tPoint);
pCursor.Size++;
// If it is larger select the right, or lower, select the left.
if (tPoint[pCursor.splitDimension] > pCursor.fSplitValue)
{
pCursor = pCursor.pRight;
}
else
{
pCursor = pCursor.pLeft;
}
}
// Insert it into the leaf.
pCursor.AddLeafPoint(tPoint, kValue);
}
/// <summary>
/// Split this leaf node by creating left and right children, then moving all the children of
/// this node into the respective buckets.
/// </summary>
private void SplitLeafNode()
{
// Create the new children.
pRight = new KDNode_Rednaxela <T>(dimensions, bucketCapacity);
pLeft = new KDNode_Rednaxela <T>(dimensions, bucketCapacity);
// Move each item in this leaf into the children.
for (int i = 0; i < Size; ++i)
{
// Store.
double[] tOldPoint = points[i];
T kOldData = data[i];
// If larger, put it in the right.
if (tOldPoint[splitDimension] > fSplitValue)
{
pRight.AddLeafPoint(tOldPoint, kOldData);
}
// If smaller, put it in the left.
else
{
pLeft.AddLeafPoint(tOldPoint, kOldData);
}
}
// Wipe the data from this KDNode.
points = null;
data = null;
}
private void CheckSinglePoint(KDNode_Rednaxela <T> pCursor)
{
// Work out the distance between this point and the search point.
double fDistance = kDistanceFunction.Distance(pCursor.points[0], tSearchPoint);
//// Skip if the point exceeds the threshold.
//// Technically this should never happen, but be prescise.
//if (fThreshold >= 0 && fDistance >= fThreshold)
// continue;
// Add the point if either need more points or it's closer than furthest on list so far.
if (pEvaluated.Size < iPointsRemaining || fDistance <= pEvaluated.MaxKey)
{
for (int i = 0; i < pCursor.Size; ++i)
{
// If we don't need any more, replace max
if (pEvaluated.Size == iPointsRemaining)
{
pEvaluated.ReplaceMax(fDistance, pCursor.data[i], i);
}
// Otherwise insert.
else
{
pEvaluated.Insert(fDistance, pCursor.data[i], i);
}
}
}
}
/// <summary>
/// Construct a new nearest neighbour iterator.
/// </summary>
/// <param name="pRoot">The root of the tree to begin searching from.</param>
/// <param name="tSearchPoint">The point in n-dimensional space to search.</param>
/// <param name="kDistance">The distance function used to evaluate the points.</param>
/// <param name="iMaxPoints">The max number of points which can be returned by this iterator. Capped to max in tree.</param>
/// <param name="fThreshold">Threshold to apply to the search space. Negative numbers indicate that no threshold is applied.</param>
public NearestNeighbour(KDNode_Rednaxela <T> pRoot, double[] tSearchPoint, IDistanceFunction kDistance, int iMaxPoints, double fThreshold)
{
// Check the dimensionality of the search point.
if (tSearchPoint.Length != pRoot.dimensions)
{
throw new Exception("Dimensionality of search point and kd-tree are not the same.");
}
// Store the search point.
this.tSearchPoint = new double[tSearchPoint.Length];
Array.Copy(tSearchPoint, this.tSearchPoint, tSearchPoint.Length);
// Store the point count, distance function and tree root.
this.iPointsRemaining = Math.Min(iMaxPoints, pRoot.Size);
this.fThreshold = fThreshold;
this.kDistanceFunction = kDistance;
this.pRoot = pRoot;
this.iMaxPointsReturned = iMaxPoints;
_CurrentDistance = -1;
// Create an interval heap for the points we check.
this.pEvaluated = new IntervalHeap <T>();
// Create a min heap for the things we need to check.
this.pPending = new MinHeap <KDNode_Rednaxela <T> >();
this.pPending.Insert(0, pRoot);
}
private void DescendPath(KDNode_Rednaxela <T> pCursor)
{
KDNode_Rednaxela <T> pNotTaken;
// If the seach point is larger, select the right path.
if (tSearchPoint[pCursor.splitDimension] > pCursor.fSplitValue)
{
pNotTaken = pCursor.pLeft;
pCursor = pCursor.pRight;
}
else
{
pNotTaken = pCursor.pRight;
pCursor = pCursor.pLeft;
}
// Calculate the shortest distance between the search point and the min and max bounds of the kd-node.
double fDistance = kDistanceFunction.DistanceToRectangle(tSearchPoint, pNotTaken.minBound, pNotTaken.maxBound);
//// If it is greater than the threshold, skip.
//if (fThreshold >= 0 && fDistance > fThreshold)
//{
// //pPending.Insert(fDistance, pNotTaken);
// continue;
//}
// Only add the path we need more points or the node is closer than furthest point on list so far.
if (pEvaluated.Size < iPointsRemaining || fDistance <= pEvaluated.MaxKey)
{
pPending.Insert(fDistance, pNotTaken);
}
}
private void CheckSpreadOutPoints(KDNode_Rednaxela <T> pCursor)
{
// Treat the distance of each point seperately.
for (int i = 0; i < pCursor.Size; ++i)
{
// Compute the distance between the points.
double fDistance = kDistanceFunction.Distance(pCursor.points[i], tSearchPoint);
//// Skip if it exceeds the threshold.
//if (fThreshold >= 0 && fDistance >= fThreshold)
// continue;
// Insert the point if we have more to take.
if (pEvaluated.Size < iPointsRemaining)
{
pEvaluated.Insert(fDistance, pCursor.data[i], i);
}
// Otherwise replace the max.
else if (fDistance < pEvaluated.MaxKey)
{
pEvaluated.ReplaceMax(fDistance, pCursor.data[i], i);
}
}
}
/// <summary>
/// Check for the next iterator item.
/// </summary>
/// <returns>True if we have one, false if not.</returns>
public bool MoveNext()
{
// Bail if we are finished.
if (iPointsRemaining == 0)
{
_Current = default(T);
return(false);
}
// While we still have paths to evaluate.
while (pPending.Size > 0 && (pEvaluated.Size == 0 || (pPending.MinKey < pEvaluated.DistanceMin)))
{
// If there are pending paths possibly closer than the nearest evaluated point, check it out
KDNode_Rednaxela <T> pCursor = pPending.Min;
pPending.RemoveMin();
// Descend the tree, record paths not taken
while (!pCursor.IsLeaf)
{
// DescendPath(pCursor);
KDNode_Rednaxela <T> pNotTaken;
// If the seach point is larger, select the right path.
if (tSearchPoint[pCursor.splitDimension] > pCursor.fSplitValue)
{
pNotTaken = pCursor.pLeft;
pCursor = pCursor.pRight;
}
else
{
pNotTaken = pCursor.pRight;
pCursor = pCursor.pLeft;
}
// Calculate the shortest distance between the search point and the min and max bounds of the kd-node.
double fDistance = kDistanceFunction.DistanceToRectangle(tSearchPoint, pNotTaken.minBound, pNotTaken.maxBound);
//// If it is greater than the threshold, skip.
//if (fThreshold >= 0 && fDistance > fThreshold)
//{
// //pPending.Insert(fDistance, pNotTaken);
// continue;
//}
// Only add the path we need more points or the node is closer than furthest point on list so far.
if (pEvaluated.Size < iPointsRemaining || fDistance <= pEvaluated.MaxKey)
{
pPending.Insert(fDistance, pNotTaken);
}
}
// If all the points in this KD node are in one place.
if (pCursor.IsSinglePoint)
{
CheckSinglePoint(pCursor);
}
// If the points in the KD node are spread out.
else
{
CheckSpreadOutPoints(pCursor);
}
}
// Select the point with the smallest distance.
if (pEvaluated.Size == 0)
{
return(false);
}
iPointsRemaining--;
_CurrentDistance = pEvaluated.DistanceMin;
_Current = pEvaluated.ClosestPoint;
_CurrentIndex = pEvaluated.ClosestPointIndex;
pEvaluated.RemoveMin();
return(true);
}