public static int GetAlpha(IntNode node, int entry)
{
if (entry == 0)
return 0;
int branchFactor = node.Children.Count;
int sum = 0;
for (int i = 0; i <= node.Children[0].Height; i++)
sum += (int)Math.Pow(branchFactor, i);
return sum * entry;
}
/// <summary>
/// Make an IndexBucket and calculate the pointer for each entry.
/// </summary>
/// <param name="node">The node to make the bucket of</param>
/// <param name="start">Index of entry of this node to be used to
/// start this bucket.</param>
/// <param name="offset"></param>
/// <param name="rep"></param>
/// <returns></returns>
public static IndexBucket MakeIndexBucket(IntNode node, int start,
int offset, int rep)
{
IndexBucket bucket = new IndexBucket();
int entry = 0;
for (int i = start; i < node.Children.Count; i++)
{
int index = GetAlpha(node, entry);
if (rep > 0)
index += entry;
if (rep > 1)
index += GetBeta(node.Children.Count, rep, entry);
index += (offset + 1);
bucket.AddEntry(new IndexEntry(node.Children[i].Bounds,
index));
entry++;
}
return bucket;
}
private void BuildTree(List<Point> records, Orthotope bounds,
int branchFactor)
{
int dimensions = records[0].Dimensions;
int height = ApproxTreeHeight(records.Count, branchFactor);
//Assign partitions to each dimension.
int[] dimensionPartitions = GetPartitionPerDimension(
GetPartitionPowerFactor(dimensions, height),
branchFactor);
//Get cell width for each dimension
double[] cellWidths = GetPartitionWidth(bounds, dimensionPartitions);
//Make Leaves
List<Node> leaves = MakeLeaves(bounds, dimensionPartitions,
cellWidths);
//Build the tree bottom up from leaves.
List<Node> nodes = leaves;
while (true)
{
if (nodes.Count == 1)
{
root = nodes[0];
break;
}
List<Node> newNodes = new List<Node>();
for (int i = 0; i < (int)(nodes.Count / branchFactor); i++)
{
IntNode node = new IntNode(
nodes.GetRange(i * branchFactor, branchFactor));
newNodes.Add(node);
}
nodes = newNodes;
}
}