C# Linq 交集、并集、差集、去重

其实只要明白 LINQ查询操作符的

Distinct、Union、Concat、Intersect、Except、Skip、Take、SkipWhile、TakeWhile、Single、SingleOrDefault、Reverse、SelectMany,Aggregate()(这个挺偏的，具体意思有空再写，可以百度一下)

的使用，一些简单的操作就可以了。
合并两个数组,并去掉重复元素,然后排序(C#)

 List<int> numbers1 = new List<int>() { 5, 4, 1, 3, 9, 8, 6, 7, 12, 10 };            List<int> numbers2 = new List<int>() { 15, 14, 11, 13, 19, 18, 16, 17, 12, 10 };            var newQuerty = numbers1.Concat(            from n in numbers2            where !numbers1.Contains(n)            select n            ).OrderBy(n => n);            string count = "";            foreach (int i in newQuerty)            {                count += i + ",";            }            MessageBox.Show(count);
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在这简单的介绍几个关键字，Distinct、Union、Concat、Intersect、Except、Skip、Take
Distinct - 过滤集合中的相同项；

   List<int> list= new List<int>() {1,2,3,4,4,5,6,6 };  var newlist=list.Distinct();
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得到的结果就是；1,2,3,4,5,6

Union - 连接不同集合，自动过滤相同项

 List<int> list= new List<int>() {1,2,3,4,4,5,6,6 };List<int> list1= new List<int>() {5,6,6,7,8,9};  var newlist=list.Union (list1);
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得到的结果就是；1,2,3,4,5,6,7,8,9

Concat - 连接不同集合，不会自动过滤相同项；

 List<int> list= new List<int>() {1,2,3,4,4,5,6,6 };List<int> list1= new List<int>() {5,6,6,7,8,9};  var newlist=list.Union (list1);
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得到的结果就是；1,2,3,4,4,5,6,6,5,6,6,7,8,9

Intersect - 获取不同集合的相同项（交集）；

List<int> list= new List<int>() {1,2,3,4,4,5,6,6 };List<int> list1= new List<int>() {5,6,6,7,8,9};  var newlist=list.Intersect (list1);
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得到的结果就是；5,6

Except - 从某集合中删除其与另一个集合中相同的项；其实这个说简单点就是某集合中独有的元素

List<int> list= new List<int>() {1,2,3,4,4,5,6,6 };List<int> list1= new List<int>() {5,6,6,7,8,9};  var newlist=list.Except (list1);
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得到的结果就是；1,2,3,4

Skip - 跳过集合的前n个元素；

List<int> list= new List<int>() {1,2,3,4,4,5,6,6 };  var newlist=list.Skip (3);
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得到的结果就是；4,4,5,6,6

Take - 获取集合的前n个元素；延迟

List<int> list= new List<int>() {1,2,2,3,4,4,5,6,6 };  var newlist=list.Take (3);
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得到的结果就是；1,2,2

List<string> ListA = new List<string>();List<string> ListB = new List<string>();List<string> ListResult = new List<string>();ListResult = ListA.Distinct().ToList();//去重ListResult = ListA.Except(ListB).ToList();//差集ListResult= ListA.Union(ListB).ToList();  //并集ListResult = ListA.Intersect(ListB).ToList();//交集
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重写比较方法

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Data; namespace test{    class Program    {        static void Main(string[] args)        {            IList<Student> oneStudents = new List<Student>();            oneStudents.Add(new Student(1,false,"小新1","徐汇"));            oneStudents.Add(new Student(2,false,"小新2","闵行"));            oneStudents.Add(new Student(3, false, "小新3", "嘉定"));            oneStudents.Add(new Student(4, false, "小新4", "闸北"));            IList<Student> twoStudents = new List<Student>();            twoStudents.Add(new Student(5, false, "小新5", "贵州"));            twoStudents.Add(new Student(6, false, "小新6", "湖北"));            twoStudents.Add(new Student(7, false, "小新7", "山东"));            twoStudents.Add(new Student(8, false, "小新8", "西藏"));            IList<Student> threeStudents = new List<Student>();            threeStudents.Add(new Student(1, false, "小新1", "徐汇"));            threeStudents.Add(new Student(2, false, "小新2", "闵行"));            var bingji = oneStudents.Union(twoStudents, new StudentListEquality()).ToList();//并（全）集               var jiaoji = oneStudents.Intersect(threeStudents, new StudentListEquality()).ToList();//交集               var chaji = oneStudents.Except(threeStudents, new StudentListEquality()).ToList();//差集              Console.WriteLine();            Console.WriteLine("以下是并集的结果");                        bingji.ForEach(x =>            {                Console.WriteLine(x.StudentId.ToString() + "    " + x.Sex.ToString() + "   " + x.Name.ToString()+" "+x.Address.ToString());            });            Console.WriteLine();            Console.WriteLine("以下是交集的结果");                       jiaoji.ForEach(x =>            {                Console.WriteLine(x.StudentId.ToString() + "    " + x.Sex.ToString() + "   " + x.Name.ToString() + " " + x.Address.ToString());            });            Console.WriteLine();            Console.WriteLine("以下是差集的结果");                        chaji.ForEach(x =>            {                Console.WriteLine(x.StudentId.ToString() + "    " + x.Sex.ToString() + "   " + x.Name.ToString() + " " + x.Address.ToString());            });        }    }    public class Student    {        public Student(int studentId, bool sex, String name, String address)        {            this.StudentId = studentId;            this.Sex = sex;            this.Name = name;            this.Address = address;        }        public int StudentId { get; set; }        public bool Sex { get; set; }        public String Name { get; set; }        public String Address { get; set; }    }    public class StudentListEquality : IEqualityComparer<Student>    {        public bool Equals(Student x, Student y)        {            return x.StudentId == y.StudentId;        }        public int GetHashCode(Student obj)        {            if (obj == null)            {                return 0;            }            else            {                return obj.ToString().GetHashCode();            }        }    }}
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