Question

我想将以下for循环代码转换为LINQ以提高可读性。 for循环工作正常。然而，LINQ给了我错误，任何人都可以指出我错误的地方吗？

for (int i = 1; i <= dataset.Count(); i++)
{
            string source = dataset.First(e => e.ID == i).SourceMachine.Trim();
            string target = dataset.First(e => e.ID == i).TargetMachine.Trim();
            int count = dataset.First(e => e.ID == i).Connection;
            GraphEdge edge = new GraphEdge(source, target, count);
            edgeList.Add(edge);
}

我的错误LINQ就像：

var edges = dataset.Select(e => new GraphEdge
    {
        Source = e.SourceMachine.Trim(),
        Target = e.TargetMachine.Trim(),
        Weight = e.Connection
    }).ToList();

仅供参考：

IQueryable<SeedTest> dataset = builder.GetAllSeedTest();


 public partial class SeedTest
  {
    public string SourceMachine { get; set; }
    public string TargetMachine { get; set; }
    public int Connection { get; set; }
    public int ID { get; set; }
  }

更新GraphEdge类

public class GraphEdge : IEdge<string>
    {
        public GraphEdge(string s, string t, int w)
        {
            Source = s;
            Target = t;
            Weight = w;
        }

        public string Source { get; set; }
        public string Target { get; set; }
        public int Weight { get; set; }
    }

Answer 1

虽然在这里使用linq似乎并不合适，但如果你想要，你仍然可以尝试：

var edges = dataset.Select(t =>
            {
                var obj = dataset.First(m => dataset.IndexOf(t).Equals(t.ID));
                return new GraphEdge(obj.SourceMachine.Trim(), obj.TargetMachine.Trim(), obj.Connection);
            }).ToArray();

希望它有所帮助。

Answer 2

你在做的不是Linq。你正在一个类中初始化变量试试这样的事情。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            GraphEdge graphEdge = new GraphEdge();
            var edges = graphEdge.dataset.Select(e => new GraphEdge()
            {
                Source = e.SourceMachine.Trim(),
                Target = e.TargetMachine.Trim(),
                Weight = e.Connection
            }).ToList();

        }
    }
    public class GraphEdge
    {

        public string Source { get; set; }
        public string Target { get; set; }
        public int Weight { get; set; }

        public IQueryable<SeedTest> dataset = builder.GetAllSeedTest();

        public GraphEdge()
        {
        }
        public GraphEdge(string s, string t, int w)
        {
            Source = s;
            Target = t;
            Weight = w;
        }

        public partial class SeedTest
        {
        public string SourceMachine { get; set; }
        public string TargetMachine { get; set; }
        public int Connection { get; set; }
        public int ID { get; set; }
        }

    }
}

Answer 3

GraphEdge没有默认构造函数（没有参数的构造函数）。我怀疑这样做会很好：

var edges = dataset.Select(e => new GraphEdge(
        e.SourceMachine.Trim(),
        e.TargetMachine.Trim(),
        e.Connection)).ToList();

将For循环转换为LINQ导致的错误

3 个答案: