Class UnaryUnionOp

Unions a Collection of Geometrys or a single Geometry (which may be a GeometryCollection) together.

Inheritance

object

UnaryUnionOp

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: NetTopologySuite.Operation.Union

Assembly: NetTopologySuite.dll

Syntax

public class UnaryUnionOp

Remarks

By using this special-purpose operation over a collection of geometries it is possible to take advantage of various optimizations to improve performance.

Heterogeneous GeometryCollections are fully supported.

The result obeys the following contract:

• Unioning a set of Polygons has the effect of merging the areas (i.e. the same effect as iteratively unioning all individual polygons together).
• Unioning a set of LineStrings has the effect of fully noding and dissolving the input linework. In this context "fully noded" means that there will be an endpoint or node in the result for every endpoint or line segment crossing in the input. "Dissolved" means that any duplicate (e.g. coincident) line segments or portions of line segments will be reduced to a single line segment in the output. This is consistent with the semantics of the Union(Geometry) operation. If merged linework is required, the LineMerger class can be used.
• Unioning a set of Points has the effect of merging all identical points (producing a set with no duplicates).

UnaryUnion always operates on the individual components of MultiGeometries. So it is possible to use it to "clean" invalid self-intersecting MultiPolygons (although the polygon components must all still be individually valid.)

Constructors

UnaryUnionOp(Geometry)

Constructs a unary union operation for a Geometry (which may be a GeometryCollection).

Declaration

public UnaryUnionOp(Geometry geom)

Parameters

Type	Name	Description
Geometry	geom	A geometry to union

UnaryUnionOp(IEnumerable<Geometry>)

Constructs a unary union operation for an enumeration of Geometrys, using the GeometryFactory of the input geometries.

Declaration

public UnaryUnionOp(IEnumerable<Geometry> geoms)

Parameters

Type	Name	Description
IEnumerable<Geometry>	geoms	An enumeration of geometries

UnaryUnionOp(IEnumerable<Geometry>, GeometryFactory)

Constructs a unary union operation for an enumeration of Geometrys.

If no input geometries were provided but a GeometryFactory was provided,

Declaration

public UnaryUnionOp(IEnumerable<Geometry> geoms, GeometryFactory geomFact)

Parameters

Type	Name	Description
IEnumerable<Geometry>	geoms	An enumeration of geometries
GeometryFactory	geomFact	The geometry factory to use if the enumeration is empty

Properties

UnionStrategy

Declaration

public UnionStrategy UnionStrategy { get; set; }

Property Value

Type	Description
UnionStrategy

Remarks

Named setter named setUnionFun[ction] in JTS

Methods

Union()

Gets the union of the input geometries.

The result of empty input is determined as follows:

Declaration

public Geometry Union()

Returns

Type	Description
Geometry	A Geometry containing the union, or an empty atomic geometry, or an empty GEOMETRYCOLLECTION, ornull if no GeometryFactory was provided

Union(Geometry)

Constructs a unary union operation for a Geometry (which may be a GeometryCollection).

Declaration

public static Geometry Union(Geometry geom)

Parameters

Type	Name	Description
Geometry	geom	A geometry to union

Returns

Type	Description
Geometry	The union of the elements of the geometry or an empty GEOMETRYCOLLECTION

Union(IEnumerable<Geometry>)

Computes the geometric union of a IEnumerable<T>

Declaration

public static Geometry Union(IEnumerable<Geometry> geoms)

Parameters

Type	Name	Description
IEnumerable<Geometry>	geoms	A collection of geometries

Returns

Type	Description
Geometry	The union of the geometries, or null if the input is empty

Union(IEnumerable<Geometry>, GeometryFactory)

Computes the geometric union of a IEnumerable<T>

If no input geometries were provided but a GeometryFactory was provided, an empty GeometryCollection is returned.

Declaration

public static Geometry Union(IEnumerable<Geometry> geoms, GeometryFactory geomFact)

Parameters

Type	Name	Description
IEnumerable<Geometry>	geoms	A collection of geometries
GeometryFactory	geomFact	The geometry factory to use if the collection is empty

Returns

Type	Description
Geometry	The union of the geometries or an empty GEOMETRYCOLLECTION