运算符将数据基于一个共同的共享属性放入一些分组
操作 | 描述 | C#查询表达式语法 | VB查询表达式语法 |
---|---|---|---|
GroupBy | 组织项目的顺序组,并将其返回IEnumerable类型的集合IGrouping<key, element> | group … by -or- group … by … into … | Group … By … Into … |
ToLookup | 执行在其中的密钥对的序列被返回分组运算 | 不适用 | 不适用 |
GroupBy示例- 查询表达式
C#
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Operators { class Program { static void Main(string[] args) { List<int> numbers = new List<int>() { 35, 44, 200, 84, 3987, 4, 199, 329, 446, 208 }; IEnumerable<IGrouping<int, int>> query = from number in numbers group number by number % 2; foreach (var group in query) { Console.WriteLine(group.Key == 0 ? "\nEven numbers:" : "\nOdd numbers:"); foreach (int i in group) Console.WriteLine(i); } Console.ReadLine(); } } }
VB
Module Module1 Sub Main() Dim numbers As New System.Collections.Generic.List(Of Integer)( New Integer() {35, 44, 200, 84, 3987, 4, 199, 329, 446, 208}) Dim query = From number In numbers Group By Remainder = (number Mod 2) Into Group For Each group In query Console.WriteLine(If(group.Remainder = 0, vbCrLf &"Even numbers:", vbCrLf &"Odd numbers:")) For Each num In group.Group Console.WriteLine(num) Next Next Console.ReadLine() End Sub End Module
当在C#或VB上面的代码被编译和执行时,它产生了以下结果:
Odd numbers: 35 3987 199 329 Even numbers: 44 200 84 4 446 208