diff --git a/LinqStudy.Test/LinqToObject/GroupTest.cs b/LinqStudy.Test/LinqToObject/GroupTest.cs
new file mode 100644
index 0000000..c511165
--- /dev/null
+++ b/LinqStudy.Test/LinqToObject/GroupTest.cs
@@ -0,0 +1,168 @@
+using System.Collections;
+using System.Collections.Generic;
+
+using System.Linq;
+
+using Xunit;
+
+using LinqStudy;
+
+namespace LinqStudy.Test.LinqToObject
+{
+ ///
+ /// 分组操作符
+ ///
+ public class GroupTest
+ {
+ ///
+ /// GroupBy: 根据指定的键选择器函数对序列的元素进行分组;延迟执行。
+ /// 注意：Key即分组依据，可以常用的值类型，也可以是引用类型(可以自定义比较器))
+ ///
+ [Fact]
+ public void GroupBy_Default_Test()
+ {
+ List peoples=new List()
+ {
+ new Person(){Id=1, Name="Andy", Age=10},
+ new Person(){Id=2, Name="Bab", Age=20},
+ new Person(){Id=3, Name="Babs", Age=20},
+ new Person(){Id=4, Name="Cara", Age=30},
+ new Person(){Id=5, Name="Carlton", Age=30},
+ new Person(){Id=6, Name="Cora", Age=30},
+ new Person(){Id=7, Name="Dawn", Age=40},
+ new Person(){Id=8, Name="Debby", Age=40},
+ new Person(){Id=9, Name="Dotty", Age=40},
+ new Person(){Id=10, Name="Dove", Age=40},
+ };
+
+ var group = peoples.GroupBy(p=>p.Age);
+ var groupCount = group.Count();
+
+ Assert.Equal(4,groupCount);
+ }
+
+ ///
+ /// 延迟执行
+ ///
+ [Fact]
+ public void GroupBy_Delay_Test()
+ {
+ List peoples=new List()
+ {
+ new Person(){Id=1, Name="Andy", Age=10},
+ new Person(){Id=2, Name="Bab", Age=20},
+ new Person(){Id=3, Name="Babs", Age=20},
+ new Person(){Id=4, Name="Cara", Age=30},
+ new Person(){Id=5, Name="Carlton", Age=30},
+ new Person(){Id=6, Name="Cora", Age=30},
+ };
+
+ var group = peoples.GroupBy(p=>p.Age);
+
+ //改变数据源
+ List peoples2=new List()
+ {
+ new Person(){Id=7, Name="Dawn", Age=40},
+ new Person(){Id=8, Name="Debby", Age=40},
+ new Person(){Id=9, Name="Dotty", Age=40},
+ new Person(){Id=10, Name="Dove", Age=40},
+ };
+ peoples.AddRange(peoples2);
+
+ //受数据源变化的影响，说明是延迟执行。
+ var groupCount = group.Count();
+
+ Assert.Equal(4,groupCount);
+ }
+
+ ///
+ /// 重载：keySelector， comparer
+ /// key：是引用类型，使用自定义比较器
+ ///
+ [Fact]
+ public void GroupBy_keySelector_comparer_Test()
+ {
+ List peoples=new List()
+ {
+ new Teacher(){Id=1, Name="河南周口人", Hometown=new Hometown(){Province="河南", City="周口"}},
+ new Teacher(){Id=2, Name="俺河南周口哩", Hometown=new Hometown(){Province="河南",City="周口"}},
+ new Teacher(){Id=3, Name="上海宝山人", Hometown=new Hometown(){Province="上海",City="宝山"}},
+ new Teacher(){Id=4, Name="上海松江人", Hometown=new Hometown(){Province="上海",City="松江"}},
+
+ };
+
+ var group = peoples.GroupBy(p=>p.Hometown,new HometownEqualityComparer());
+
+ var groupFirstNames=group.First().Select(q=>q.Name).ToList();
+ var expected=new List(){"河南周口人","俺河南周口哩"};
+
+ Assert.Equal(expected,groupFirstNames);
+ }
+
+ ///
+ /// 重载：keySelector， elementSelector
+ /// key：是引用类型，使用自定义比较器
+ ///
+ [Fact]
+ public void GroupBy_keySelector_elementSelector_Test()
+ {
+ List peoples=new List()
+ {
+ new Teacher(){Id=1, Name="河南周口人", Hometown=new Hometown(){Province="河南", City="周口"}},
+ new Teacher(){Id=1, Name="俺河南周口哩", Hometown=new Hometown(){Province="河南",City="周口"}},
+ new Teacher(){Id=2, Name="上海宝山人", Hometown=new Hometown(){Province="上海",City="宝山"}},
+ new Teacher(){Id=3, Name="上海松江人", Hometown=new Hometown(){Province="上海",City="松江"}},
+
+ };
+
+ var group = peoples.GroupBy(p=>p.Id,t=>t.Name).ToList();
+
+ var groupFirstNames=group[2].FirstOrDefault();
+ var expected="上海松江人";
+
+ Assert.Equal(expected,groupFirstNames);
+ }
+ ///
+ /// 重载：keySelector elementSelector comparer
+ ///
+ [Fact]
+ public void GroupBy_keySelector_elementSelector_comparer_Test()
+ {
+ List peoples=new List()
+ {
+ new Teacher(){Id=1, Name="河南周口人", Hometown=new Hometown(){Province="河南", City="周口"}},
+ new Teacher(){Id=2, Name="俺河南周口哩", Hometown=new Hometown(){Province="河南",City="周口"}},
+ new Teacher(){Id=3, Name="上海宝山人", Hometown=new Hometown(){Province="上海",City="宝山"}},
+ new Teacher(){Id=4, Name="上海松江人", Hometown=new Hometown(){Province="上海",City="松江"}},
+
+ };
+
+ var group = peoples.GroupBy(p=>p.Hometown,t=>t.Name,new HometownEqualityComparer()).ToList();
+
+ var groupFirstNames=group[2].FirstOrDefault();
+ var expected="上海松江人";
+
+ Assert.Equal(expected,groupFirstNames);
+ }
+
+ [Fact]
+ public void GroupBy_keySelector_resultSelector_Test()
+ {
+ List peoples=new List()
+ {
+ new Teacher(){Id=1, Name="河南周口人", Hometown=new Hometown(){Province="河南", City="周口"}},
+ new Teacher(){Id=1, Name="俺河南周口哩", Hometown=new Hometown(){Province="河南",City="周口"}},
+ new Teacher(){Id=3, Name="上海宝山人", Hometown=new Hometown(){Province="上海",City="宝山"}},
+ new Teacher(){Id=4, Name="上海松江人", Hometown=new Hometown(){Province="上海",City="松江"}},
+
+ };
+
+ var group = peoples.GroupBy(p=>p.Id, (key,teacher) => teacher.Select(t=>t.Name)).ToList();
+
+ var groupFirstNames=group[2].FirstOrDefault();
+ var expected="上海松江人";
+
+ Assert.Equal(expected,groupFirstNames);
+ }
+ }
+}
\ No newline at end of file
diff --git a/LinqStudy.Test/LinqToObject/标准查询操作符.md b/LinqStudy.Test/LinqToObject/标准查询操作符.md
index f1bcd91..f52e3ce 100644
--- a/LinqStudy.Test/LinqToObject/标准查询操作符.md
+++ b/LinqStudy.Test/LinqToObject/标准查询操作符.md
@@ -31,11 +31,13 @@
## 相等操作符
## 量词操作符
+
Any
All
## 分区操作符
+
Take 返回序列中,从0开始的连续指定项数据子序列；延迟执行。
- TakeWhile
\ No newline at end of file
+ TakeWhile
diff --git a/LinqStudy/Models/Hometown.cs b/LinqStudy/Models/Hometown.cs
new file mode 100644
index 0000000..570a23c
--- /dev/null
+++ b/LinqStudy/Models/Hometown.cs
@@ -0,0 +1,21 @@
+using System;
+
+namespace LinqStudy
+{
+ ///
+ /// 家乡类
+ ///
+ public class Hometown
+ {
+ ///
+ /// 省份
+ ///
+ ///
+ public string Province{get;set;}
+
+ ///
+ /// 城市
+ ///
+ public string City{get;set;}
+ }
+}
diff --git a/LinqStudy/Models/HometownCompare.cs b/LinqStudy/Models/HometownCompare.cs
new file mode 100644
index 0000000..f81e968
--- /dev/null
+++ b/LinqStudy/Models/HometownCompare.cs
@@ -0,0 +1,44 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace LinqStudy
+{
+ ///
+ /// 家乡 比较器
+ ///
+ public class HometownCompare : IComparer
+ {
+ int IComparer.Compare(Hometown x, Hometown y)
+ {
+ int compareResult = 0;
+
+ if (x == null && y == null)
+ {
+ compareResult = 0;
+ }
+
+ else if (x == null)
+ {
+ compareResult = 1;
+ }
+ else if (y == null)
+ {
+ compareResult = -1;
+ }
+ else
+ {
+ if(x.Province == y.Province)
+ {
+ compareResult = string.Compare(x.City,y.City);
+ }
+ else
+ {
+ compareResult = string.Compare(x.Province,y.Province);
+ }
+ }
+
+ return compareResult;
+ }
+ }
+}
diff --git a/LinqStudy/Models/HometownEqualityComparer.cs b/LinqStudy/Models/HometownEqualityComparer.cs
new file mode 100644
index 0000000..6e1b397
--- /dev/null
+++ b/LinqStudy/Models/HometownEqualityComparer.cs
@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+
+namespace LinqStudy
+{
+ ///
+ /// 家乡类 相等比较器
+ ///
+ public class HometownEqualityComparer : IEqualityComparer
+ {
+ bool IEqualityComparer.Equals(Hometown x, Hometown y)
+ {
+ if (x==null || y==null)
+ {
+ return false;
+ }
+
+ return x.Province == y.Province && x.City == y.City;
+ }
+
+ int IEqualityComparer.GetHashCode(Hometown obj)
+ {
+ return (obj.Province+obj.City).GetHashCode();
+ }
+ }
+}
diff --git a/LinqStudy/Models/Person.cs b/LinqStudy/Models/Person.cs
index da45934..c2e8be5 100644
--- a/LinqStudy/Models/Person.cs
+++ b/LinqStudy/Models/Person.cs
@@ -3,7 +3,7 @@ using System;
namespace LinqStudy
{
///
- ///
+ /// 人类
///
public class Person
{
diff --git a/LinqStudy/Models/PersonCompare.cs b/LinqStudy/Models/PersonCompare.cs
index d2eec98..57541e6 100644
--- a/LinqStudy/Models/PersonCompare.cs
+++ b/LinqStudy/Models/PersonCompare.cs
@@ -4,7 +4,7 @@ using System.Collections.Generic;
namespace LinqStudy
{
///
- /// PersonȽIdΪȽϱ
+ /// Person 比较器
///
public class PersonComparer : IComparer
{
diff --git a/LinqStudy/Models/PersonEqualityComparerByName.cs b/LinqStudy/Models/PersonEqualityComparerByName.cs
new file mode 100644
index 0000000..e9a4bf7
--- /dev/null
+++ b/LinqStudy/Models/PersonEqualityComparerByName.cs
@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+
+namespace LinqStudy
+{
+ public class PersonEqualityComparerByName : IEqualityComparer
+ {
+ bool IEqualityComparer.Equals(Person x, Person y)
+ {
+ if (x==null || y==null)
+ {
+ return false;
+ }
+
+ return x.Name == y.Name;
+ }
+
+ int IEqualityComparer.GetHashCode(Person obj)
+ {
+ return (obj.Name).GetHashCode();
+ }
+ }
+}
diff --git a/LinqStudy/Models/Teacher.cs b/LinqStudy/Models/Teacher.cs
new file mode 100644
index 0000000..1cf33ca
--- /dev/null
+++ b/LinqStudy/Models/Teacher.cs
@@ -0,0 +1,25 @@
+using System;
+
+namespace LinqStudy
+{
+ ///
+ /// 老师
+ ///
+ public class Teacher
+ {
+ ///
+ /// Id
+ ///
+ public int Id {get;set;}
+
+ ///
+ /// 姓名
+ ///
+ public string Name{get;set;}
+
+ ///
+ /// 家乡
+ ///
+ public Hometown Hometown{get;set;}
+ }
+}
diff --git a/LinqStudy/Models/TeacherCompare.cs b/LinqStudy/Models/TeacherCompare.cs
new file mode 100644
index 0000000..ca993ab
--- /dev/null
+++ b/LinqStudy/Models/TeacherCompare.cs
@@ -0,0 +1,61 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using LinqStudy;
+
+namespace LinqStudy
+{
+ ///
+ /// 家乡 比较器
+ ///
+ public class TeacherCompare : IComparer
+ {
+ int IComparer.Compare(Teacher x, Teacher y)
+ {
+ int compareResult = 0;
+
+ if (x == null && y == null)
+ {
+ compareResult = 0;
+ }
+
+ else if (x == null)
+ {
+ compareResult = 1;
+ }
+ else if (y == null)
+ {
+ compareResult = -1;
+ }
+ else
+ {
+ if(x.Id == y.Id)
+ {
+ if(x.Name==y.Name)
+ {
+ IComparer homeCompare= new HometownCompare();
+ compareResult= homeCompare.Compare(x.Hometown, y.Hometown);
+ }
+ else
+ {
+ compareResult = string.Compare(x.Name,y.Name);
+ }
+
+ }
+ else
+ {
+ if(x.Id>y.Id)
+ {
+ compareResult =1;
+ }
+ else
+ {
+ compareResult = -1;
+ }
+ }
+ }
+
+ return compareResult;
+ }
+ }
+}