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()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);
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();
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);
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);
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);
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);
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);
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);
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
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(); } } } }