Class HPRtree<T>

A Hilbert-Packed R-tree. This is a static R-tree which is packed by using the Hilbert ordering of the tree items.

The tree is constructed by sorting the items by the Hilbert code of the midpoint of their envelope. Then, a set of internal layers is created recursively as follows:

• The items/nodes of the previous are partitioned into blocks of size nodeCapacity
• For each block a layer node is created with range equal to the envelope of the items/nodess in the block

The internal layers are stored using an array to store the node bounds. The link between a node and its children is stored implicitly in the indexes of the array. For efficiency, the offsets to the layers within the node array are pre-computed and stored.

NOTE: Based on performance testing, the HPRtree is somewhat faster than the STRtree. It should also be more memory-efficent, due to fewer object allocations.

However, it is not clear whether this will produce a significant improvement for use in JTS operations.

Inheritance

object

HPRtree<T>

Implements

ISpatialIndex<T>

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: NetTopologySuite.Index.HPRtree

Assembly: NetTopologySuite.dll

Syntax

public class HPRtree<T> : ISpatialIndex<T>

Type Parameters

Name	Description
T

Constructors

HPRtree()

Creates a new index with the default node capacity.

Declaration

public HPRtree()

HPRtree(int)

Creates a new index with the given node capacity.

Declaration

public HPRtree(int nodeCapacity)

Parameters

Type	Name	Description
int	nodeCapacity	The node capacity to use

Properties

Count

Gets the number of items in the index.

Declaration

public int Count { get; }

Property Value

Type	Description
int	The number of items

Methods

Build()

Builds the index, if not already built.

Declaration

public void Build()

GetBounds()

Gets the extents of the internal index nodes

Declaration

public Envelope[] GetBounds()

Returns

Type	Description
Envelope[]	A list of the internal node extents

Insert(Envelope, T)

Adds a spatial item with an extent specified by the given Envelope to the index.

Declaration

public void Insert(Envelope itemEnv, T item)

Parameters

Type	Name	Description
Envelope	itemEnv
T	item

Query(Envelope)

Queries the index for all items whose extents intersect the given search Envelope Note that some kinds of indexes may also return objects which do not in fact intersect the query envelope.

Declaration

public IList<T> Query(Envelope searchEnv)

Parameters

Type	Name	Description
Envelope	searchEnv	The envelope to query for.

Returns

Type	Description
IList<T>	A list of the items found by the query.

Query(Envelope, IItemVisitor<T>)

Queries the index for all items whose extents intersect the given search Envelope, and applies an IItemVisitor<T> to them. Note that some kinds of indexes may also return objects which do not in fact intersect the query envelope.

Declaration

public void Query(Envelope searchEnv, IItemVisitor<T> visitor)

Parameters

Type	Name	Description
Envelope	searchEnv	The envelope to query for.
IItemVisitor<T>	visitor	A visitor object to apply to the items found.

Remove(Envelope, T)

Removes a single item from the tree.

Declaration

public bool Remove(Envelope itemEnv, T item)

Parameters

Type	Name	Description
Envelope	itemEnv	The Envelope of the item to remove.
T	item	The item to remove.

Returns

Type	Description
bool	true if the item was found.

Remarks

Not supported, will always return false

Implements

ISpatialIndex<T>

See Also

STRtree<TItem>