CODEWITHSUNDEEP
c#linq
catlovespurple
catlovespurple

Reputation: 692

Convert For loop into LINQ caused errors

I want to convert the following for-loop code into LINQ to improve readability. The for loop works fine. However, LINQ gave me errors and can anyone point me out where I made mistake?

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);
}

MY wrong LINQ is like:

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

FYI: 

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; }
  }

Update GraphEdge class

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; }
    }

Upvotes: 1

Views: 44

Answers (3)

Jacob Proffitt
Jacob Proffitt

Reputation: 12768

GraphEdge doesn't have a default constructor (one with no parameters). I suspect this would work just fine:

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

Upvotes: 0

ATP
ATP

Reputation: 561

Although it does not seem advantageous to use linq here but still if you want you can try:

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();

Hope it helps.

Upvotes: 1

jdweng
jdweng

Reputation: 34419

What you are doing is not Linq. You are intializing variable in a class Try something like this.

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; }
        }

    }
}​

Upvotes: 0

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