C网络拓扑结构M值

默认坐标序列为 CoordinateArraySequence 目前不支持 M 价值观,但看起来 DotSpatialAffineCoordinateSequence 支持m值。得到 米 价值观工作我必须做以下工作

using NetTopologySuite.Geometries;
using NetTopologySuite.Geometries.Implementation;
using System.Diagnostics;

namespace NetTopologyTest
{
    class Program
    {
        static void Main(string[] args)
        {
            //This sequence has to be initialized with ordinates XYZM. If you construct it
            //with just XYZ values, then you can't add M values to it later.
            var coordinateSequence = new DotSpatialAffineCoordinateSequence(new[] { 1.0, 2.0 }, new[] { 3.0 }, new[] { 4.0 });
            var sequenceFactory = new DotSpatialAffineCoordinateSequenceFactory(GeoAPI.Geometries.Ordinates.XYZM);
            var geometryFactory = new GeometryFactory(sequenceFactory);
            var p3 = new Point(coordinateSequence, geometryFactory);
            p3.Y = 8;
            p3.M = 1;
            var m = p3.M;

            Debug.WriteLine(p3);
            Debug.WriteLine(p3.M);
            Debug.WriteLine(m);
        }
    }
}

是的,它是 缺陷 的默认实现中缺少的功能 ICoordinateSequence . 看起来他们已经开始进行更改以支持m值,但是这些更改并没有在任何地方进行。下面是代码中不支持m值的至少一个区域,它最终导致了您看到的问题。

当引用p3.m时,它使用这些get和set方法。

    public double M
    {
        get
        {
            if (CoordinateSequence == null)
                throw new ArgumentOutOfRangeException("M called on empty Point");
            return CoordinateSequence.GetOrdinate(0, Ordinate.M);
        }
        set => CoordinateSequence.SetOrdinate(0, Ordinate.M, value);
    }

然后依次调用 GetOrdinate 和 SetOrdinate 在里面 CoordinateArraySequence

    /// <summary>
    /// Returns the ordinate of a coordinate in this sequence.
    /// Ordinate indices 0 and 1 are assumed to be X and Y.
    /// Ordinate indices greater than 1 have user-defined semantics
    /// (for instance, they may contain other dimensions or measure values).
    /// </summary>
    /// <param name="index">The coordinate index in the sequence.</param>
    /// <param name="ordinate">The ordinate index in the coordinate (in range [0, dimension-1]).</param>
    /// <returns></returns>
    public double GetOrdinate(int index, Ordinate ordinate)
    {
        switch (ordinate)
        {
            case Ordinate.X:
                return Coordinates[index].X;
            case Ordinate.Y:
                return Coordinates[index].Y;
            case Ordinate.Z:
                return Coordinates[index].Z;
            default:
                return double.NaN;
        }
    }

    /// <summary>
    /// Sets the value for a given ordinate of a coordinate in this sequence.
    /// </summary>
    /// <param name="index">The coordinate index in the sequence.</param>
    /// <param name="ordinate">The ordinate index in the coordinate (in range [0, dimension-1]).</param>
    /// <param name="value">The new ordinate value.</param>
    public void SetOrdinate(int index, Ordinate ordinate, double value)
    {
        switch (ordinate)
        {
            case Ordinate.X:
                Coordinates[index].X = value;
                break;
            case Ordinate.Y:
                Coordinates[index].Y = value;
                break;
            case Ordinate.Z:
                Coordinates[index].Z = value;
                break;
            //default:
            //    //throw new ArgumentException("invalid ordinate index: " + ordinate);
        }
    }

你可以看到,当你打电话 设置纵坐标 具有 Ordinate.M 什么都没准备好,打电话的时候 获得坐标 具有 纵坐标m 它总是会回来的。

如果你真的想使用nettopologysuite,你可以从这里开始回购。 https://github.com/NetTopologySuite/NetTopologySuite 并进行支持所需的更新 M 默认情况下是值,但我认为有很多事情需要更改。如果你更新了它,我相信维护nettopologysuite github repo的人会很感激一个包含任何更改的pull请求。