LINQ Samples

I will cover few examples which are using query operators. You can find list of query operators Here

Refer Player class

Code

 

public class Player

  {

      public string FirstName { get; set; }

      public string LastName { get; set; }

      public string Country { get; set; }

      public int[] Scores { get; set; }

      public int ManOfTheSeries { get; set; }

  }

 

Type Filtering

Filtering based on the type.

Code

// FILTERING

          Console.WriteLine("List of batsmans who have scrored more than 50 runs in their First Match");

          foreach (Player s in query)

              Console.WriteLine(s.FirstName + " " + s.LastName + ": " + s.Scores[0]);

           // Keep the console window open in debug mode.

           //TYPE FILTERING

           //GET the int data from the type which contains both string and int.

           object[] sampleObject = {1,2,"Three",4,5,"Six","Seven",

                                           new Player{

                                                       FirstName = "Virat",

                                                       LastName="Kohli",

                                                       Country="India", 

                                                       Scores = new int[] { 107, 119, 125, 114 }

                                                   } 

                                   };

           //Get the string 

           var queryTypeFilteringString = sampleObject.OfType<string>();

           Console.WriteLine("");

           Console.WriteLine("String Type");

           foreach (var item in queryTypeFilteringString)

           {

               Console.WriteLine(item);

           }

           //Get the Int

           var queryTypeFilteringInt = sampleObject.OfType<int>();

           Console.WriteLine("");

           Console.WriteLine("Int Type");

           foreach (var item in queryTypeFilteringInt)

           {

               Console.WriteLine(item);

           }

           //Get Player

           var queryTypeFilteringPlayer = sampleObject.OfType<Player>();

           Console.WriteLine("");

           Console.WriteLine("Player Type");

           foreach (var item in queryTypeFilteringPlayer)

           {

               Console.WriteLine(item.FirstName + " "+ item.LastName);

           }

Output

String Type

Three

Six

Seven

Int Type

1

2

4

5

Player Type

Virat Kohli

Press any key to exit.

Compound Form

Below query will provide list of batsmans who have scored century (100) and above.

Code

            //Compound

            Console.WriteLine("List of batsman who have scored Century (100) in their Matches");

            var queryFilter = playerList

                              .SelectMany(

                               p=>p.Scores,

                              (p,s) => new {Player=p,Score=s})

                             .Where(p => p.Score > 100)

                             .OrderBy(p=>p.Player.FirstName)

                             .Select(a => a.Player.FirstName +" "+a.Player.LastName + " " + Convert.ToString(a.Score) );

            foreach (string s in queryFilter)

                     Console.WriteLine(s);

Output

Hashim Amla 165

Mahela Jayawardene 185

Ricky Ponting 180

Ricky Ponting 142

Sachin Tendulkar 200

Sachin Tendulkar 190

Sachin Tendulkar 170

Sachin Tendulkar 150

Press any key to exit.

Sorting
The OrderBy() and OrderByDescending() Methds returns IOrderedEnumerable<TSource>.

Code

//Indian Players with their scores, descending order by LastName

           var sortQuery = playerList

                           .SelectMany(p => p.Scores,

                           (p, s) => new { Player = p, Score = s })

                           .Where(p => p.Player.Country == "India")

                           .OrderByDescending(p => p.Player.LastName)

                            .Select(p => p);

Output

Sachin Tendulkar India 200

Sachin Tendulkar India 190

Sachin Tendulkar India 170

Sachin Tendulkar India 150

Virender Sehwag India 225

Virender Sehwag India 170

Virender Sehwag India 184

Virender Sehwag India 102

Press any key to exit.

Group By

To Group query results based on a key value ,the  group clause can be used.

Code

// List of plyers count group by countries

            var countiresQry = from p in playerList

                               group p by p.Country into g

                               orderby g.Count() >= 2

                               select new

                                   {

                                       Country = g.Key,

                                       Count = g.Count()

                                   };

Above Query with Extension methods

var countiresQry = playerList.

                             GroupBy(p=>p.Country).

                             OrderByDescending(g=>g.Count()).

                             ThenBy(g=>g.Key).

                             Where(g=>g.Count()>1).

                             Select(g=>new {Country= g.Key, Count=g.Count()});

Output

India      2

Australia  2

Sri Lanka  2

South Africa 2

Press any key to exit.

Grouping With Nested Objects

Code

var countiresQry = playerList.

                              GroupBy(p=>p.Country).

                              OrderByDescending(g=>g.Count()).

                              ThenBy(g=>g.Key).

                              Where(g=>g.Count()>=2).

                              Select(g=>new 

                                   {

                                       Country= g.Key, 

                                       Count=g.Count(),

                                       Players = g.OrderBy(r => r.LastName).Select(r => r.FirstName + " " + r.LastName)

                               });

           foreach (var item in countiresQry)

           {

               Console.WriteLine("Country:{0,-10}  Plyer Count:{1}", item.Country, item.Count);

               foreach (var name in item.Players)

               {

                   Console.Write(" Player Name:{0}\n ",name);

               }

               Console.WriteLine();

           }

Output

Country:Australia   Plyer Count:2

 Player Name:Adam Gilchrist

  Player Name:Ricky Ponting

Country:India       Plyer Count:2

 Player Name:Virender Sehwag

  Player Name:Sachin Tendulkar

Country:South Africa  Plyer Count:2

 Player Name:Hashim Amla

  Player Name:Graeme Smith

Country:Sri Lanka   Plyer Count:2

 Player Name:Mahela Jayawardene

  Player Name:Kumar Sangakara

Press any key to exit.