Grouping a Collection using Linq in various ways

In this post we  are going to see how to grouping a collection in Linq

public abstract class Person

{

    public int ID { set; get; }

    public string Name { set; get; }

    public int PhoneNumber { set; get; }

    public string Address { set; get; }

}

public class Student:Person

{

    public string Department { set; get; }

    public int TotalMarks { set; get; }

}

        List<Student> StudentList = new List<Student>() {

            new Student(){ ID =4,

Name="Suresh",

Address="Porur",

TotalMarks=350,

Department="ECE",

PhoneNumber=12321312

},

            new Student(){ ID=2,

Name="Ramu",

Address="Delhi",

TotalMarks=450,

Department="CSE",

PhoneNumber=23233112

},

             new Student(){

ID=1,

Name="Rajesh",

Address="Madurai",

TotalMarks=400,

Department="ECE",

PhoneNumber=3434322

},

            new Student(){

ID=3,

Name="Rajesh",

Address="Chennai",

TotalMarks=460,

Department="CSE",

PhoneNumber=43434223

},

            new Student(){

ID=5,

Name="Hanish",

Address="Salem",

TotalMarks=420,

Department="EEE",

PhoneNumber=34423232

}

        };

IEnumerable<IGrouping<string,Student>> grpstuds = StudentList.GroupBy(x => x.Department);

Console.WriteLine("Grouping Students Linq .... ");

        

foreach (var item in grpstuds)

{

        Console.WriteLine(string.Format("Department : {0}", item.Key));

        foreach (var stu in item)

        {

            Console.WriteLine(string.Format("ID : {0}, Name {1}", stu.ID, stu.Name));

        }

 }

Output:

*************

Grouping Students Linq ....

Department : ECE
ID : 4, Name Suresh
ID : 1, Name Rajesh

Department : CSE
ID : 2, Name Ramu
ID : 3, Name Rajesh

Department : EEE
ID : 5, Name Hanish.

        varsqlgrpstuds =    from stud in StudentList

                            group stud by stud.Department into grp

                            select grp;

        Console.WriteLine("Grouping Students Linq to Sql .... ");

        foreach (var item in sqlgrpstuds)

        {

            Console.WriteLine(string.Format("Department : {0}", item.Key));

            foreach (var stu in item)

            {

                Console.WriteLine(string.Format("ID : {0}, Name {1}", stu.ID, stu.Name));

            }

        }

        Console.Read();

Output:

*******************

Grouping Students Linq to Sql ....

Department : ECE
ID : 4, Name Suresh
ID : 1, Name Rajesh

Department : CSE
ID : 2, Name Ramu
ID : 3, Name Rajesh

Department : EEE
ID : 5, Name Hanish

From this post we can learn how to use the groupby method in Linq to group a collection in various ways