September 2, 2021

Programmingempire

In this article, I will explain how to perform Set Operations in LINQ. Basically, Language Integrated Query (LINQ) has several query methods for performing set operations such as union, intersection, and set difference.

Query Methods for Performing Set Operations in LINQ

The following section provides a description of query methods available in LINQ. In fact, we can represent a set using a collection such as an array.

In order to find the union of two sets, we can use the Union() method, which returns a set of unique elements which are available in either of the two sets. Similarly, the Intersect() method returns the set intersection comprising of the common elements in the two sets. Likewise, the Except() method returns a set difference, comprising of all the elements present in one set which are not available in the second set. Also, there is a Distinct() method that returns unique values from a set.

Examples of Set Operations in LINQ

The following code shows how to use the Union(), Except(), and Intersect() methods in a query.

using System;
using System.Linq;
namespace LINQSetOperations
{
    class Program
    {
        static void Main(string[] args)
        {
            String[] Things = {"Cart", "Umbrella", "Refrigerator", "Humidifier", "Fan", "Light", "Pump", "Playground", "Shop", "School", "Chair" };
            String[] RoomThings = { "Fan", "Light", "Bed", "Almirah", "Refrigerator", "Humidifier", "Chair"};

            Console.WriteLine("Elements of Set 1 (Things): ");
            foreach (String s in Things)
                Console.Write(s + " ");
            Console.WriteLine();

            Console.WriteLine("Elements of Set 2 (RoomThings): ");
            foreach (String s in RoomThings)
                Console.Write(s + " ");
            Console.WriteLine();

            var q1 = (from a1 in Things
                      select a1).Union(RoomThings);
            Console.WriteLine("Union of two sets...");
            foreach (String s in q1)
                Console.Write(s + " ");
            Console.WriteLine();

            var q2 = (from a1 in Things
                      select a1).Intersect(RoomThings);
            Console.WriteLine("Intersection of two sets...");
            foreach (String s in q2)
                Console.Write(s + " ");
            Console.WriteLine();

            var q3 = (from a1 in Things
                      select a1).Except(RoomThings);
            Console.WriteLine("Difference of two sets...");
            foreach (String s in q3)
                Console.Write(s + " ");
            Console.WriteLine();

        }
    }
}

Output

**Demonstrating Union, Intersection, and Difference Set Operations in LINQ**

Apart from the above operations, there is also a Distinct() method that returns unique values from a set. The following example shows how the Distinct() method works.

using System;
using System.Linq;
namespace DistinctMethodDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] arr = {1,2,2,1,1,1,1,3,4,1,2,3,3,4,7,5,6,6,5,8,9,12,14,15,1,2,8,5,70,5,5,6,16 };
            Console.WriteLine("All Elements in the Set...");
            foreach (int i in arr)
                Console.Write(i + " ");
            Console.WriteLine();

            Console.WriteLine("Distinct Elements in the Set...");
            var q = arr.Distinct();
            foreach (int i in q)
                Console.Write(i + " ");
            Console.WriteLine();
        }
    }
}

Output

Programmingempire

Query Methods for Performing Set Operations in LINQ

Examples of Set Operations in LINQ

Further Reading

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