Linq query that finds duplicates and removed them from a list [duplicate]

问题

I'm trying to create a LINQ query that will look for duplicates in 2 lists and remove them from the first list.

The code bellow will find the duplicate and return them, but I would like the query to return the unique items from notificationsFirst:

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            InnerJoinExample();
            Console.ReadLine();
        }

        class Notification
        {
            public string Name { get; set; }
            public int Id { get; set; }
        }

        public static void InnerJoinExample()
        {
            Notification first = new Notification { Name = "First", Id = 1 };
            Notification second = new Notification { Name = "Second", Id = 2 };
            Notification third = new Notification { Name = "Third", Id = 3 }; 
            Notification fourth = new Notification { Name = "Fourth", Id = 4 };
            Notification fifth = new Notification { Name = "Fifth", Id = 5 };

            List<Notification> notificationsFirst = new List<Notification> { first, second, third };
            List<Notification> notificationsSecond = new List<Notification> { third, fourth, fifth };

            var query = from notiFirst in notificationsFirst
                        join notiSecond in notificationsSecond on notiFirst.Id equals notiSecond.Id
                        select new Notification { Name = notiFirst.Name, Id = notiFirst.Id };


            foreach (var not in query)
            {
                Console.WriteLine($"\"{not.Name}\" with Id {not.Id}");
            }
        }

        // This code should produce the following:
        //
        // "First" with Id 1
        // "Second" with Id 2
    }
}

回答1:

You should use Except method in combination with Intersect.

The idea is to find out the intersection list of the given initial lists using Intersect and then just Except that list from first collection.

var query = notificationsFirst.Except(notificationsFirst.Intersect(notificationsSecond));

来源：https://stackoverflow.com/questions/65594332/linq-query-that-finds-duplicates-and-removed-them-from-a-list

标签

linq