/// <summary>
/// Method to get the nodes of a specic level
/// </summary>
/// <param name="level"></param>
/// <returns></returns>
public IList <SbnNode> GetNodesOfLevel(int level)
{
if (level < 1 || level > NumLevels)
{
throw new ArgumentOutOfRangeException("level");
}
var start = (int)Math.Pow(2, level - 1);
var end = 2 * start - 1;
return(NumPySlicing.GetRange(Nodes, start, end, 1));
}
//private class SbnBinEnumerator : IEnumerator<SbnBin>
//{
// private readonly SbnTree _tree;
// private SbnNode _currentNode;
// private SbnBin _currentBin, _lastBin;
// private bool _finished;
// public SbnBinEnumerator(SbnTree tree)
// {
// _tree = tree;
// }
// public void Dispose()
// {
// }
// public bool MoveNext()
// {
// if (_finished)
// return false;
// _lastBin = _currentBin;
// var res = SeekNextBin(1);
// Debug.Assert(!ReferenceEquals(_lastBin, _currentBin));
// return res;
// }
// bool SeekNextBin(int depth)
// {
// Debug.Assert(depth < 1000);
// if (_currentNode == null)
// {
// _currentNode = _tree.Nodes[1];
// if (_currentNode.FirstBin == null)
// return SeekNextBin(depth+1);
// }
// if (_currentBin == null)
// {
// _currentBin = _currentNode.FirstBin;
// if (_currentBin == null)
// {
// if (_currentNode.Nid == _tree.LastLeafNodeId)
// {
// _finished = true;
// return false;
// }
// _currentNode = _tree.Nodes[_currentNode.Nid + 1];
// return SeekNextBin(depth + 1);
// }
// return true;
// }
// _currentBin = _currentBin.Next;
// if (_currentBin == null)
// {
// if (_currentNode.Nid == _tree.LastLeafNodeId)
// {
// _finished = true;
// return false;
// }
// _currentNode = _tree.Nodes[_currentNode.Nid + 1];
// return SeekNextBin(depth + 1);
// }
// return true;
// }
// public void Reset()
// {
// _currentNode = null;
// _currentBin = null;
// _finished = false;
// }
// public SbnBin Current { get { return _currentBin; } }
// object IEnumerator.Current
// {
// get { return Current; }
// }
//}
/// <summary>
/// Method to compute the number of features in a given level
/// </summary>
/// <param name="level">The level</param>
/// <returns>The number of features</returns>
public int FeaturesInLevel(int level)
{
// return the number of features in a level
var start = (int)Math.Pow(2, level - 1);
var end = 2 * start - 1;
var featureCount = 0;
foreach (var n in NumPySlicing.GetRange(Nodes, start, end - start + 1))
{
featureCount += n.FeatureCount;
}
return(featureCount);
}
/// <summary>
/// Method to compact this <see cref="SbnTree"/>.
/// </summary>
private void CompactSeamFeatures()
{
// the mystery algorithm - compaction? optimization? obfuscation?
if (NumLevels < 4)
{
return;
}
var start = FirstLeafNodeId / 2 - 1;
if (start < 3)
{
start = 3;
}
var end = start / 8;
if (end < 1)
{
end = 1;
}
foreach (var node in NumPySlicing.GetRange(Nodes, start, end, -1))
{
var id = node.Nid;
var children = NumPySlicing.GetRange(Nodes, id * 2, 2);
foreach (var child in children)
{
// There are no items to pull up
if (child.FeatureCount == 0)
{
continue;
}
var cid = child.Nid;
var grandchildren = NumPySlicing.GetRange(Nodes, cid * 2, 2);
var gccount = 0;
foreach (var gcnode in grandchildren)
{
gccount += gcnode.FeatureCount;
}
//Debug.WriteLine("Node {0} has {1} GC", id, gccount);
if (gccount == 0)
{
//Debug.WriteLine("Slurping {0} features from node {1}", child.AllFeatures().Count, child.id);
//node.features.AddRange(child.features);
// this is weird but it works
if (child.FeatureCount < 4)
{
if (node.FirstBin == null)
{
node.FirstBin = new SbnBin();
}
//for (var i = 0; i < child.FeatureCount; i++)
//{
// //node.LastBin.AddFeature(child.FirstBin[i]);
// node.LastBin.AddFeature(child.RemoveAt(0));
//}
while (child.FeatureCount > 0)
{
node.LastBin.AddFeature(child.RemoveAt(0));
}
//Debug.Assert(child.FeatureCount == 0);
//child.FirstBin = null;
}
}
}
}
Built = true;
}
