Class LengthIndexedLine

Supports linear referencing along a linear Geometry using the length along the line as the index. Negative length values are taken as measured in the reverse direction from the end of the geometry. Out-of-range index values are handled by clamping them to the valid range of values. Non-simple lines (i.e. which loop back to cross or touch themselves) are supported.

Inheritance

object

LengthIndexedLine

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: NetTopologySuite.LinearReferencing

Assembly: NetTopologySuite.dll

Syntax

public class LengthIndexedLine

Constructors

LengthIndexedLine(Geometry)

Constructs an object which allows a linear Geometry to be linearly referenced using length as an index.

Declaration

public LengthIndexedLine(Geometry linearGeom)

Parameters

Type	Name	Description
Geometry	linearGeom	The linear geometry to reference along.

Properties

EndIndex

Returns the index of the end of the line.

Declaration

public double EndIndex { get; }

Property Value

Type	Description
double

StartIndex

Returns the index of the start of the line.

Declaration

public double StartIndex { get; }

Property Value

Type	Description
double

Methods

ClampIndex(double)

Computes a valid index for this line by clamping the given index to the valid range of index values

Declaration

public double ClampIndex(double index)

Parameters

Type	Name	Description
double	index

Returns

Type	Description
double	A valid index value

ExtractLine(double, double)

Computes the LineString for the interval on the line between the given indices. If the endIndex lies before the startIndex, the computed geometry is reversed.

Declaration

public Geometry ExtractLine(double startIndex, double endIndex)

Parameters

Type	Name	Description
double	startIndex
double	endIndex

Returns

Type	Description
Geometry

ExtractPoint(double)

Computes the Coordinate for the point on the line at the given index. If the index is out of range the first or last point on the line will be returned.

Declaration

public Coordinate ExtractPoint(double index)

Parameters

Type	Name	Description
double	index	The index of the desired point.

Returns

Type	Description
Coordinate	The Coordinate at the given index.

Remarks

The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.

ExtractPoint(double, double)

Computes the Coordinate for the point on the line at the given index, offset by the given distance.

Declaration

public Coordinate ExtractPoint(double index, double offsetDistance)

Parameters

Type	Name	Description
double	index	The index of the desired point
double	offsetDistance	The distance the point is offset from the segment (positive is to the left, negative is to the right)

Returns

Type	Description
Coordinate	The Coordinate at the given index

Remarks

If the index is out of range the first or last point on the line will be returned. The computed point is offset to the left of the line if the offset distance is positive, to the right if negative. The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.

IndexOf(Coordinate)

Computes the minimum index for a point on the line. If the line is not simple (i.e. loops back on itself) a single point may have more than one possible index. In this case, the smallest index is returned. The supplied point does not necessarily have to lie precisely on the line, but if it is far from the line the accuracy and performance of this function is not guaranteed. Use Project(Coordinate) to compute a guaranteed result for points which may be far from the line.

Declaration

public double IndexOf(Coordinate pt)

Parameters

Type	Name	Description
Coordinate	pt	A point on the line.

Returns

Type	Description
double	The minimum index of the point.

See Also

Project(Coordinate)

IndexOfAfter(Coordinate, double)

Finds the index for a point on the line which is greater than the given index. If no such index exists, returns minIndex. This method can be used to determine all indexes for a point which occurs more than once on a non-simple line. It can also be used to disambiguate cases where the given point lies slightly off the line and is equidistant from two different points on the line. The supplied point does not necessarily have to lie precisely on the line, but if it is far from the line the accuracy and performance of this function is not guaranteed. Use Project(Coordinate) to compute a guaranteed result for points which may be far from the line.

Declaration

public double IndexOfAfter(Coordinate pt, double minIndex)

Parameters

Type	Name	Description
Coordinate	pt	A point on the line.
double	minIndex	The value the returned index must be greater than.

Returns

Type	Description
double	The index of the point greater than the given minimum index.

See Also

Project(Coordinate)

IndicesOf(Geometry)

Computes the indices for a subline of the line. (The subline must conform to the line; that is, all vertices in the subline (except possibly the first and last) must be vertices of the line and occur in the same order).

Declaration

public double[] IndicesOf(Geometry subLine)

Parameters

Type	Name	Description
Geometry	subLine	A subLine of the line.

Returns

Type	Description
double[]	A pair of indices for the start and end of the subline..

IsValidIndex(double)

Tests whether an index is in the valid index range for the line.

Declaration

public bool IsValidIndex(double index)

Parameters

Type	Name	Description
double	index	The index to test.

Returns

Type	Description
bool	true if the index is in the valid range.

Project(Coordinate)

Computes the index for the closest point on the line to the given point. If more than one point has the closest distance the first one along the line is returned. (The point does not necessarily have to lie precisely on the line.)

Declaration

public double Project(Coordinate pt)

Parameters

Type	Name	Description
Coordinate	pt

Returns

Type	Description
double