c# - LINQ，创建集合的唯一集合

Question

我有

class Vertex{
    Graph _graph;
    float x;
    float y;
    string key;
    //and some similar atributes
    public IEnumerable<Edge> Edges{
        get{
            return _graph.Edges.Where(s => s.Source == this);
        }
    }
}
class Edge{
    Graph _graph;
    Vertex source;
    Vertex target;
}
class Graph
{
    private VertexCollection _vertexCollection; // extends List<Vertex>
    private EdgeCollection _edgeCollection; //extends List<Edge>
    public IEnumerable<Vertex> Vertexes
    {
        get
        {
            return _vertexCollection;
        }
    }
    public IEnumerable<Edge> Edges
    {
        get
        {
            return _edgeCollection;
        }
    }
    public IDictionary<Edge, bool> DrawableEdges
    {
        get
        {
            //want to return my uniq dictionary
        }
    }    

Edges和 Vertexes被收集到列表中

一些例子:

A-->B // edge from vertex A to B
B-->C // edge from vertex B to C
C-->A // edge from vertex C to A
A-->C // edge from vertex A to C  -- this is two way edge

所以我想制作IDictionary<Edge, bool>它将保持边缘(A-->B 和 B-->A 就像 1)，以及 bool - 如果它是双向的或否。

我需要它，因为当我现在绘制它们时，它会在彼此下方绘制 2 个箭头。我最好做 1 个箭头。

所以我被困在这里......有人可以帮助我吗？

Answer 1

我认为你应该实现 IEquatable Edge 的界面类:

public class Edge : IEquatable<Edge>
{
    ...

    public bool Equals(Edge other)
    {
        return (
            (other.Source == this.Source && other.Target == this.Target) ||
            (other.Target == this.Source && other.Source == this.Target));
    }

    public override int GetHashCode()
    {
        return (Source.GetHashCode() ^ Target.GetHashCode());
    }
}

并将你的边添加到 HashSet<Edge>收藏。然后你可以调用它的Contains方法来检查它是否包含边缘。

编辑:正如 Henk 所说，您还可以实现自定义 IEqualityComparer类:

public sealed class EdgeComparer : IEqualityComparer<Edge>
{
    public static EdgeComparer Default { get; private set; }

    static EdgeComparer()
    {
        Default = new EdgeComparer();
    }

    private EdgeComparer()
    {
    }

    public bool Equals(Edge x, Edge y)
    {
        return (
            (x.Source == y.Source && x.Target == y.Target) ||
            (x.Target == y.Source && x.Source == y.Target));
    }

    public int GetHashCode(Edge edge)
    {
        return (edge.Source.GetHashCode() ^ edge.Target.GetHashCode());
    }
}

并用

初始化你的哈希集

_drawableEdges = new HashSet<Edge>(EdgeComparer.Default);