/// <summary>
/// RTree constructor. Initializes the root.
/// </summary>
public RTree()
{
root = new NodeRecord <T> {
Node = new RTreeNode <T>(Leaf: true)
};
}
/// <summary>
/// Utilizes the Quadradic split algorithm to determine where each
/// of the records go - either to group one or group two.
/// </summary>
/// <param name="newItem"></param>
/// <returns></returns>
public NodeRecord <T> SplitQuadradic(IndexRecord <T> newItem)
{
List <IndexRecord <T> > itemsToBeAssigned = records;
itemsToBeAssigned.Add(newItem);
IndexRecord <T> A, B;
// QS1.
pickSeeds(itemsToBeAssigned, out A, out B);
itemsToBeAssigned.Remove(A);
itemsToBeAssigned.Remove(B);
NodeRecord <T> groupOne = new NodeRecord <T>()
{
BBox = A.BBox, Node = new RTreeNode <T>(isLeaf)
};
NodeRecord <T> groupTwo = new NodeRecord <T>()
{
BBox = B.BBox, Node = new RTreeNode <T>(isLeaf)
};
groupOne.Node.TryInsert(A);
groupTwo.Node.TryInsert(B);
// QS2.
while (itemsToBeAssigned.Count > 0)
{
// QS3.
int d1, d2;
var next = pickNext(itemsToBeAssigned, groupOne, groupTwo, out d1, out d2);
if (d1 < d2)
{
groupOne.TryInsert(next);
}
else if (d2 < d1)
{
groupTwo.TryInsert(next);
}
else
{
// Insert to whichever is smaller.
if (groupOne.Node.GetRecordCount() < groupTwo.Node.GetRecordCount())
{
groupOne.TryInsert(next);
}
else
{
groupTwo.TryInsert(next);
}
}
itemsToBeAssigned.Remove(next);
// QS2.
if (groupOne.Node.GetRecordCount() + itemsToBeAssigned.Count <= m)
{
while (itemsToBeAssigned.Count > 0)
{
groupOne.TryInsert(itemsToBeAssigned.First());
itemsToBeAssigned.Remove(itemsToBeAssigned.First());
}
}
// QS2.
if (groupTwo.Node.GetRecordCount() + itemsToBeAssigned.Count <= m)
{
while (itemsToBeAssigned.Count > 0)
{
groupTwo.TryInsert(itemsToBeAssigned.First());
itemsToBeAssigned.Remove(itemsToBeAssigned.First());
}
}
}
// Set this equal to group two.
records = groupTwo.Node.records;
return(groupOne);
}
