Esempio n. 1
0
        private bool approximate(KDTreeNode <T> current, double[] position,
                                 KDTreeNodeCollection <T> list, int maxLeaves, ref int visited)
        {
            // Compute distance from this node to the point
            double d = distance(position, current.Position);

            list.Add(current, d);

            if (++visited > maxLeaves)
            {
                return(true);
            }


            // Check for leafs on the opposite sides of
            // the subtrees to nearest possible neighbors.

            // Prepare for recursion. The following null checks
            // will be used to avoid function calls if possible

            double value  = position[current.Axis];
            double median = current.Position[current.Axis];
            double u      = value - median;

            if (u <= 0)
            {
                if (current.Left != null)
                {
                    if (approximate(current.Left, position, list, maxLeaves, ref visited))
                    {
                        return(true);
                    }
                }

                if (current.Right != null && Math.Abs(u) <= list.Maximum)
                {
                    if (approximate(current.Right, position, list, maxLeaves, ref visited))
                    {
                        return(true);
                    }
                }
            }
            else
            {
                if (current.Right != null)
                {
                    approximate(current.Right, position, list, maxLeaves, ref visited);
                }

                if (current.Left != null && Math.Abs(u) <= list.Maximum)
                {
                    if (approximate(current.Left, position, list, maxLeaves, ref visited))
                    {
                        return(true);
                    }
                }
            }

            return(false);
        }
Esempio n. 2
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        private void nearest(KDTreeNode <T> current, double[] position, KDTreeNodeCollection <T> list)
        {
            // Compute distance from this node to the point
            double d = distance(position, current.Position);

            if (current.IsLeaf)
            {
                // Base: node is leaf
                list.Add(current, d);
            }
            else
            {
                // Check for leafs on the opposite sides of
                // the subtrees to nearest possible neighbors.

                // Prepare for recursion. The following null checks
                // will be used to avoid function calls if possible

                double value  = position[current.Axis];
                double median = current.Position[current.Axis];
                double u      = (value - median);

                if (u < 0)
                {
                    if (current.Left != null)
                    {
                        nearest(current.Left, position, list);
                    }

                    list.Add(current, d);

                    if (current.Right != null)
                    {
                        if ((u * u) < list.Distance.Max)
                        {
                            nearest(current.Right, position, list);
                        }
                    }
                }
                else
                {
                    if (current.Right != null)
                    {
                        nearest(current.Right, position, list);
                    }

                    list.Add(current, d);

                    if (current.Left != null)
                    {
                        if ((u * u) < list.Distance.Max)
                        {
                            nearest(current.Left, position, list);
                        }
                    }
                }
            }
        }
Esempio n. 3
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        /// <summary>
        ///   Retrieves a fixed point of nearest points to a given point.
        /// </summary>
        /// 
        /// <param name="position">The queried point.</param>
        /// <param name="neighbors">The number of neighbors to retrieve.</param>
        /// 
        /// <returns>A list of neighbor points, ordered by distance.</returns>
        /// 
        public KDTreeNodeCollection<T> Nearest(double[] position, int neighbors)
        {
            var list = new KDTreeNodeCollection<T>(size: neighbors);

            if (root != null)
                nearest(root, position, list);

            return list;
        }
Esempio n. 4
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        /// <summary>
        ///   Retrieves a fixed point of nearest points to a given point.
        /// </summary>
        ///
        /// <param name="position">The queried point.</param>
        /// <param name="neighbors">The number of neighbors to retrieve.</param>
        ///
        /// <returns>A list of neighbor points, ordered by distance.</returns>
        ///
        public KDTreeNodeCollection <T> Nearest(double[] position, int neighbors)
        {
            var list = new KDTreeNodeCollection <T>(size: neighbors);

            if (root != null)
            {
                find(root, position, neighbors, list);
            }

            return(list);
        }
Esempio n. 5
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        /// <summary>
        ///   Retrieves the nearest points to a given point within a given radius.
        /// </summary>
        ///
        /// <param name="position">The queried point.</param>
        /// <param name="radius">The search radius.</param>
        /// <param name="maximum">The maximum number of neighbors to retrieve.</param>
        ///
        /// <returns>A list of neighbor points, ordered by distance.</returns>
        ///
        public KDTreeNodeCollection <T> Nearest(double[] position, double radius, int maximum)
        {
            var list = new KDTreeNodeCollection <T>(maximum);

            if (root != null)
            {
                find(root, position, radius, list);
            }

            return(list);
        }
Esempio n. 6
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        /// <summary>
        ///   Retrieves a fixed point of nearest points to a given point.
        /// </summary>
        ///
        /// <param name="position">The queried point.</param>
        /// <param name="neighbors">The number of neighbors to retrieve.</param>
        /// <param name="maxLeaves">The maximum number of leaf nodes that can
        /// be visited before the search finishes with an approximate answer.</param>
        ///
        /// <returns>A list of neighbor points, ordered by distance.</returns>
        ///
        public KDTreeNodeCollection <T> ApproximateNearest(double[] position, int neighbors, int maxLeaves)
        {
            var list = new KDTreeNodeCollection <T>(size: neighbors);

            if (root != null)
            {
                int visited = 0;
                approximate(root, position, list, maxLeaves, ref visited);
            }

            return(list);
        }
Esempio n. 7
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        /// <summary>
        ///   Retrieves a fixed point of nearest points to a given point.
        /// </summary>
        /// 
        /// <param name="position">The queried point.</param>
        /// <param name="neighbors">The number of neighbors to retrieve.</param>
        /// <param name="percentage">The maximum percentage of leaf nodes that
        /// can be visited before the search finishes with an approximate answer.</param>
        /// 
        /// <returns>A list of neighbor points, ordered by distance.</returns>
        /// 
        public KDTreeNodeCollection<T> ApproximateNearest(double[] position, int neighbors, double percentage)
        {
            int maxLeaves = (int)(leaves * percentage);

            var list = new KDTreeNodeCollection<T>(size: neighbors);

            if (root != null)
            {
                int visited = 0;
                approximate(root, position, list, maxLeaves, ref visited);
            }

            return list;
        }
Esempio n. 8
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        /// <summary>
        ///   Retrieves the nearest points to a given point within a given radius.
        /// </summary>
        /// 
        /// <param name="position">The queried point.</param>
        /// <param name="radius">The search radius.</param>
        /// <param name="maximum">The maximum number of neighbors to retrieve.</param>
        /// 
        /// <returns>A list of neighbor points, ordered by distance.</returns>
        /// 
        public ICollection<KDTreeNodeDistance<T>> Nearest(double[] position, double radius, int maximum)
        {
            if (maximum == 0)
            {
                var list = new KDTreeNodeList<T>();

                if (root != null)
                    nearest(root, position, radius, list);

                return list;
            }
            else
            {
                var list = new KDTreeNodeCollection<T>(maximum);

                if (root != null)
                    nearest(root, position, radius, list);

                return list;
            }
        }