public void BuildTree(KDNode currentNode, List <Feature> features, bool useXAxis)
{
if (useXAxis)
{
features = features.OrderBy(i => i.X).ToList();
}
else
{
features = features.OrderBy(i => i.Y).ToList();
}
Feature med = FeatureHelper.GetMedianFeatureFromList(features);
var node = InsertNode(currentNode, med, true);
var splitFeatures = FeatureHelper.SplitFeatures(features, features.IndexOf(med));
List <Feature> leftSplit = splitFeatures[0].ToList();
List <Feature> rightSplit = splitFeatures[1].ToList();
if (leftSplit.Count <= 1)
{
if (leftSplit.Count == 1)
{
InsertNode(node, leftSplit[0], useXAxis);
}
}
else
{
this.BuildTree(node, leftSplit, !useXAxis); //alternate dimension each level we build
}
// Do the same for the right points
if (rightSplit.Count <= 1)
{
if (rightSplit.Count == 1)
{
InsertNode(node, rightSplit[0], useXAxis);
}
}
else
{
BuildTree(node, rightSplit, !useXAxis);
}
}
public void GetMedianFeature_Works_As_Expected()
{
var features = new List <Feature>();
features.Add(new Feature("place1", 1, 2));
features.Add(new Feature("place2", 2, 2));
features.Add(new Feature("place3", 3, 2));
features.Add(new Feature("place4", 4, 2));
features.Add(new Feature("place5", 5, 2));
features.Add(new Feature("place6", 6, 2));
features.Add(new Feature("place7", 7, 2));
//sort by X in test but Y is also used during building process
features = features.OrderBy(i => i.X).ToList();
var medianFeature = FeatureHelper.GetMedianFeatureFromList(features);
Assert.Equal("place4", medianFeature.Name);
}