using System;

using System.Collections.Generic;

using System.Linq;

​

public enum DType {

    DatOne,

    DisOne

}

​

public class Dat {

    public string Dis {get; set;}

    public DType DType {get;set;}

}

​

public class Program

{

    public static void Main()

    {

        var list = new Dat[] {

            new Dat { Dis = "a", DType = DType.DatOne },

            new Dat { Dis = "b", DType = DType.DisOne }

        };

        var dic = list.GroupBy(item => item.DType)

            .ToDictionary(x => x.Key, x => x.Select(tag => tag.Dis).ToList());

        Console.WriteLine(dic[DType.DisOne].First());

    }

}