LINQ分組操作

運算符將數據基於一個共同的共享屬性放入一些分組

操作

描述

C#查詢表達式語法

VB查詢表達式語法

GroupBy

組織項目的順序組，並將其返回IEnumerable類型的集合IGrouping<key, element>

group … by -or- group … by … into …

Group … By … Into …

ToLookup

執行在其中的密鑰對的序列被返回分組運算

不適用

不適用

GroupBy示例- 查詢表達式

C#

using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Operators { class Program { static void Main(string[] args) { List numbers = new List() { 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

當在C＃或VB上面的代碼被編譯和執行時，它產生了以下結果：

Odd numbers:
35
3987
199
329

Even numbers:
44
200
84
4
446
208