/// <summary>
/// Search for closest elements to the given query in increasing order of distance (L2)
/// </summary>
public IEnumerable <T> Find(IVector x)
{
// Setup the priority queue for the search
_pq = new PriorityQueue <PQEntry, PQEntry>();
_closest = new Vector(x.Dimensions);
// Search is started at root
this.Tree.InternalBounds.Closest(x, ref _closest);
double dist2 = VectorReductions.SquaredL2NormDistance(x, _closest);
if (dist2 <= this.SquaredDistanceLimit)
{
PQEntry root_entry = PQEntry.CreateNodeEntry(dist2, this.Tree);
_pq.Push(root_entry, root_entry);
}
int found = 0;
while (found < this.CountLimit && _pq.Count > 0)
{
PQEntry entry = _pq.Pop();
if (entry.NodeEntry)
{
this.ProcessNodeEntry(entry, x);
}
else
{
yield return(entry.Element);
found += 1;
}
}
}
/// <summary>
/// Process a node
/// </summary>
private void ProcessNodeEntry(PQEntry entry, IVector x)
{
KdNode <T> node = entry.Node;
double dist2;
if (node.Leaf)
{
foreach (T t in node.Vectors)
{
dist2 = VectorReductions.SquaredL2NormDistance(x, t);
if (dist2 <= this.SquaredDistanceLimit)
{
PQEntry e = PQEntry.CreateElementEntry(dist2, t);
_pq.Push(e, e);
}
}
}
else
{
node.Left.InternalBounds.Closest(x, ref _closest);
dist2 = VectorReductions.SquaredL2NormDistance(x, _closest);
if (dist2 <= this.SquaredDistanceLimit)
{
PQEntry left = PQEntry.CreateNodeEntry(dist2, node.Left);
_pq.Push(left, left);
}
node.Right.InternalBounds.Closest(x, ref _closest);
dist2 = VectorReductions.SquaredL2NormDistance(x, _closest);
if (dist2 <= this.SquaredDistanceLimit)
{
PQEntry right = PQEntry.CreateNodeEntry(dist2, node.Right);
_pq.Push(right, right);
}
}
}
