public void FromDataTest()
{
// This is the same example found in Wikipedia page on
// k-d trees: http://en.wikipedia.org/wiki/K-d_tree
// Suppose we have the following set of points:
double[][] points =
{
new double[] { 2, 3 },
new double[] { 5, 4 },
new double[] { 9, 6 },
new double[] { 4, 7 },
new double[] { 8, 1 },
new double[] { 7, 2 },
};
// To create a tree from a set of points, we use
KDTree<int> tree = KDTree.FromData<int>(points);
// Now we can manually navigate the tree
KDTreeNode<int> node = tree.Root.Left.Right;
// Or traverse it automatically
foreach (KDTreeNode<int> n in tree)
{
double[] location = n.Position;
Assert.AreEqual(2, location.Length);
}
// Given a query point, we can also query for other
// points which are near this point within a radius
double[] query = new double[] { 5, 3 };
// Locate all nearby points within an Euclidean distance of 1.5
// (answer should be a single point located at position (5,4))
var result = tree.Nearest(query, radius: 1.5);
// We can also use alternate distance functions
tree.Distance = new Manhattan();
// And also query for a fixed number of neighbor points
// (answer should be the points at (5,4), (7,2), (2,3))
var neighbors = tree.Nearest(query, neighbors: 3);
Assert.IsTrue(node.IsLeaf);
Assert.IsFalse(tree.Root.IsLeaf);
Assert.AreEqual(1, result.Count);
Assert.AreEqual("(5,4)", result[0].Node.ToString());
Assert.AreEqual(3, neighbors.Count);
Assert.AreEqual("(5,4)", neighbors[0].Node.ToString());
Assert.AreEqual("(7,2)", neighbors[1].Node.ToString());
Assert.AreEqual("(2,3)", neighbors[2].Node.ToString());
Assert.AreEqual(7, tree.Root.Position[0]);
Assert.AreEqual(2, tree.Root.Position[1]);
Assert.AreEqual(0, tree.Root.Axis);
Assert.AreEqual(5, tree.Root.Left.Position[0]);
Assert.AreEqual(4, tree.Root.Left.Position[1]);
Assert.AreEqual(1, tree.Root.Left.Axis);
Assert.AreEqual(9, tree.Root.Right.Position[0]);
Assert.AreEqual(6, tree.Root.Right.Position[1]);
Assert.AreEqual(1, tree.Root.Right.Axis);
Assert.AreEqual(2, tree.Root.Left.Left.Position[0]);
Assert.AreEqual(3, tree.Root.Left.Left.Position[1]);
Assert.AreEqual(0, tree.Root.Left.Left.Axis);
Assert.AreEqual(4, tree.Root.Left.Right.Position[0]);
Assert.AreEqual(7, tree.Root.Left.Right.Position[1]);
Assert.AreEqual(0, tree.Root.Left.Right.Axis);
Assert.AreEqual(8, tree.Root.Right.Left.Position[0]);
Assert.AreEqual(1, tree.Root.Right.Left.Position[1]);
Assert.AreEqual(0, tree.Root.Right.Left.Axis);
Assert.IsNull(tree.Root.Right.Right);
}