/// <summary>
/// Simple copy constructor that assumes the structure of the existing KD Tree is
/// intact
/// </summary>
/// <param name="_toCopy">The KD Tree to copy</param>
private void CopyConstructor(KDTree <T> _toCopy)
{
m_axisCount = _toCopy.m_axisCount;
m_selector = _toCopy.m_selector;
m_count = _toCopy.m_count;
m_distanceFunction = _toCopy.m_distanceFunction;
m_tree = _toCopy.m_tree.Clone();
}
/// <summary>
/// Construct a new K-D Tree, using the default selector for objects. This is a
/// performance-hindered version, as it relies on
/// <see cref="IMultiDimensionalPoint"/> .
/// </summary>
public KDTree()
{
m_distanceFunction = GetMultiDimensionalDistance;
if (!IsTMultiDimensional())
{
throw new InvalidOperationException("The underlying type " + typeof(T).ToString() + " does not implement IMultidimensionalPoint and no selector was specified.");
}
m_tree = new SparseLeafBinaryTree <T>(1023);
}
/// <summary>
/// Construct a new K-D Tree, using the specified selector for objects
/// </summary>
public KDTree(int _axisCount, Func <T, int, double> _selector, Func <T, T, double> _distanceFunction = null)
{
if (_axisCount < 1)
{
throw new ArgumentOutOfRangeException("Axis Count", _axisCount, "Axis Count must be greater than 1");
}
m_selector = _selector ?? throw new ArgumentNullException("_selector", "The selector cannot be null");
m_axisCount = _axisCount;
m_distanceFunction = _distanceFunction ?? GetMultiDimensionalDistance;
m_tree = new SparseLeafBinaryTree <T>(1023);
}
/// <summary>
/// Create a shallow copy of this binary tree
/// </summary>
/// <returns></returns>
public SparseLeafBinaryTree <T> Clone()
{
var clone = new SparseLeafBinaryTree <T>(m_root.Length)
{
m_root = (T[])m_root.Clone()
};
foreach (var kv in m_leaves)
{
clone.m_leaves[kv.Key] = kv.Value;
}
return(clone);
}
/// <summary>
/// Set up the K-D Tree based on an enumeration of elements. If the enumeration is
/// another KDTree of type T, then a copy constructor <see cref="Clone"/> will be
/// used.
/// </summary>
/// <param name="_collection">The collection of objects</param>
/// <param name="_axisCount">
/// The number of dimensions present in this KD Tree... use default if T implements
/// <see cref="IMultiDimensionalPoint"/>
/// </param>
/// <param name="_selector">
/// The selector to use on the objects- if NULL, relies on the objects to implement
/// <see cref="IMultiDimensionalPoint"/>
/// </param>
/// <param name="_distanceFunction">
/// A function that determines the distance between two nodes in the tree. Assumes
/// Distances are measured using double precision floating point scalar values.
/// </param>
/// <remarks>
/// If _axisCount == -1 and/or _selector == null, then T MUST implement
/// <see cref="IMultiDimensionalPoint"/> .
/// </remarks>
/// <exception cref="ArgumentOutOfRangeException">
/// Thrown if _axisCount is less than 1 AND T is not an implementation of
/// ArgumentOutOfRangeException
/// </exception>
/// <exception cref="ArgumentNullException">
/// Thrown if _selector is NULL AND T is not an implementation of
/// ArgumentOutOfRangeException
/// </exception>
/// <exception cref="ArgumentException">
/// Thrown if _axisCount is less than 1 AND there are no elements in the
/// collection, even if T implements <see cref="IMultiDimensionalPoint"/> .
/// </exception>
public KDTree(IEnumerable <T> _collection, int _axisCount = -1, Func <T, int, double> _selector = null, Func <T, T, double> _distanceFunction = null)
{
if (_collection is KDTree <T> ) // we know the internal storage is already a KD Tree- simply copy it
{
CopyConstructor(_collection as KDTree <T>);
return;
}
m_distanceFunction = _distanceFunction ?? GetMultiDimensionalDistance;
if (!IsTMultiDimensional())
{
if (_axisCount < 1)
{
throw new ArgumentOutOfRangeException("Axis Count", _axisCount, "Axis Count must be at least 1");
}
if (_selector == null)
{
throw new ArgumentNullException("_selector", "The selector cannot be null if T doesn't inherit IMultiDimensionalPoint");
}
}
if (_axisCount > 0)
{
m_axisCount = _axisCount;
}
if (_selector != null)
{
m_selector = _selector;
}
var array = _collection.ToArray(); // Construct using an array
m_tree = new SparseLeafBinaryTree <T>(array.Length);
m_count = array.Length;
if (m_count > 0)
{
if (m_axisCount < 1)
{
m_axisCount = (array[0] as IMultiDimensionalPoint).GetAxisCount();
}
BuildComparers();
ConstructFromArray(array, 0, array.Length - 1, 0, 0);
}
if (m_axisCount < 1)
{
throw new ArgumentException("May not specify an empty collection when an explicit Axis Count has not been specified");
}
}
/// <summary>
/// Use this method when a significant number of nodes have been added to the tree
/// after its construction. This has the effect of re-balancing the tree. This is
/// not a cheap operation - O(n log n)
/// </summary>
public void RebuildTree(int _capacity)
{
var items = new T[m_count];
var idx = 0;
foreach (var item in this)
{
items[idx++] = item;
}
m_tree = new SparseLeafBinaryTree <T>(_capacity);
BuildComparers();
ConstructFromArray(items, 0, items.Length - 1, 0, 0);
}
