LINQ Aggregate Function With Example

Introduction

In this article we will see about LINQ Aggregate function with an example.

Aggregate Functions in LINQ

The aggregation function is required to perform mathematical operations like Average, Aggregate, Count, Max, Min, and Sum on the numeric property of the elements in the collection.

They are,

  • Average
  • Count 
  • Min
  • Max
  • Sum

Example

using System;
using System.Collections.Generic;
using System.Linq;

namespace LinqFunctions
{
    public class Employee
    {
        public int ID { get; set; }
        public string Name { get; set; }

        public int Salary { get; set; }
        public string Dept { get; set; }
        public string Gender { get; set; }

        // internal static object GetAllEmployees()
        // {
        //     throw new NotImplementedException();
        // }

        public static List<Employee> GetAllEmployees()
        {
            List<Employee> listStudents = new List<Employee>()
            {
                new Employee{ID= 101,Name = "Preety", Salary = 16000, Dept = "IT", Gender = "Female"},
                new Employee{ID= 102,Name = "Priyanka", Salary = 15000, Dept = "Sales",  Gender = "Female"},
                new Employee{ID= 103,Name = "James", Salary = 50000, Dept = "Sales",  Gender = "Male"},
                new Employee{ID= 104,Name = "Hina", Salary = 23000, Dept = "IT", Gender = "Female"},
                new Employee{ID= 105,Name = "Anurag", Salary = 46000, Dept = "IT",  Gender = "Male"},
                new Employee{ID= 106,Name = "Sara", Salary = 25000, Dept = "IT", Gender = "Female"},
                new Employee{ID= 107,Name = "Pranaya", Salary = 35000, Dept = "IT", Gender = "Female"},
                new Employee{ID= 108,Name = "Manoj", Salary = 11000, Dept = "Sales",  Gender = "Male"},
                new Employee{ID= 109,Name = "Sam", Salary = 45000, Dept = "Sales",  Gender = "Male"},
                new Employee{ID= 110,Name = "Saurav", Salary = 25000, Dept = "Sales",  Gender = "Male"}
            };
            return listStudents;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var tableData = from TD in Employee.GetAllEmployees()
                            where TD.ID > 0
                            select (TD.ID, TD.Name, TD.Salary, TD.Dept);
            foreach (var t in tableData)
            {
                System.Console.WriteLine(t);
            }
            // To show Aggregate function 
            // int[] intNumbers = { 3, 5, 7, 9 };
            // int result = intNumbers.Aggregate((n1, n2) => n1 * n2);
            // System.Console.WriteLine(result);
            // output:945 
            System.Console.WriteLine("----------------------");
            System.Console.WriteLine("Choose the Department:");
            System.Console.WriteLine("----------------------");
            System.Console.WriteLine("1.IT");
            System.Console.WriteLine("2.Sales");
            System.Console.Write("Option: ");
            string ch = Console.ReadLine();
            int choice = Convert.ToInt32(ch);
            if (choice == 1)
            {
                var total = (from T in Employee.GetAllEmployees()
                             where T.Dept == "IT"
                             select T).Sum(T => T.Salary);
                System.Console.WriteLine("-------------------------------------");
                System.Console.WriteLine("Sum of all salary for IT : {0}", total);
                var large = (from L in Employee.GetAllEmployees()
                             where L.Dept == "IT"
                             select (L.Name, L.Salary)).Max(L => (L.Salary, L.Name));
                System.Console.WriteLine("Largest Salary: {0}", large);
                var minimum = (from M in Employee.GetAllEmployees()
                             where M.Dept == "IT"
                             select (M.Name, M.Salary)).Min(M => (M.Salary, M.Name));
                System.Console.WriteLine("Minimum Salary: {0}", minimum);
                var average = (from A in Employee.GetAllEmployees()
                             where A.Dept == "IT"
                             select (A.Name, A.Salary)).Average(A => A.Salary);
                System.Console.WriteLine("Average Salary: {0}", average);
                var number = (from N in Employee.GetAllEmployees()
                             where N.Dept == "IT"
                             select (N.Name, N.Salary)).Count();
                System.Console.WriteLine("No.of.Employees: {0}", number);
                var consist = (from C in Employee.GetAllEmployees()
                               where C.Dept == "IT"
                              select C.ID).Contains(105);
                System.Console.WriteLine("Contains ID-105: {0}",consist);
                System.Console.WriteLine("Using GroupBy, OrderBy & Key: ");
                var groupByGenderQuery = from  G in Employee.GetAllEmployees()
                                         group G by G.Gender into newGroup
                                         orderby newGroup.Key
                                         select newGroup;
                foreach (var Emp in groupByGenderQuery)
                {
                    System.Console.WriteLine($"Key: {Emp.Key}");
                    foreach (var Groups in Emp)
                    {
                        System.Console.WriteLine($"\t{Groups.Name},{Groups.Dept}");
                    }
                }
                System.Console.WriteLine("-------------------------------------");
            }
            else
            {
                var total = (from T in Employee.GetAllEmployees()
                             where T.Dept == "Sales"
                             select T).Sum(T => T.Salary);
                System.Console.WriteLine("-------------------------------------");
                System.Console.WriteLine("Sum of all salary for Sales : {0}", total);
                var large = (from L in Employee.GetAllEmployees()
                             where L.Dept == "Sales"
                             select (L.Name, L.Salary)).Max(L => (L.Salary, L.Name));
                System.Console.WriteLine("Largest Salary: {0}", large);
                                var minimum = (from M in Employee.GetAllEmployees()
                             where M.Dept == "Sales"
                             select (M.Name, M.Salary)).Min(M => (M.Salary, M.Name));
                System.Console.WriteLine("Minimum Salary: {0}", minimum);
                var average = (from A in Employee.GetAllEmployees()
                             where A.Dept == "Sales"
                             select (A.Name, A.Salary)).Average(A => A.Salary);
                System.Console.WriteLine("Average Salary: {0}", average);
                var number = (from N in Employee.GetAllEmployees()
                             where N.Dept == "Sales"
                             select (N.Name, N.Salary)).Count();
                System.Console.WriteLine("No.of.Employees: {0}", number);
                var consist = (from C in Employee.GetAllEmployees()
                              where C.Dept == "Sales"
                              select C.ID).Contains(105);
                System.Console.WriteLine("Contains ID-105: {0}",consist);
                                System.Console.WriteLine("Using GroupBy, OrderBy & Key: ");
                var groupByGenderQuery = from  G in Employee.GetAllEmployees()
                                         group G by G.Gender into newGroup
                                         orderby newGroup.Key
                                         select newGroup;
                foreach (var Emp in groupByGenderQuery)
                {
                    System.Console.WriteLine($"Key: {Emp.Key}");
                    foreach (var Groups in Emp)
                    {
                        System.Console.WriteLine($"\t{Groups.Name},{Groups.Dept}");
                    }
                }
                System.Console.WriteLine("-------------------------------------");
            }

        }
    }
}

Output

(101, Preety, 16000, IT)
(102, Priyanka, 15000, Sales)
(103, James, 50000, Sales)   
(104, Hina, 23000, IT)
(105, Anurag, 46000, IT)
(106, Sara, 25000, IT)
(107, Pranaya, 35000, IT)
(108, Manoj, 11000, Sales)
(109, Sam, 45000, Sales)
(110, Saurav, 25000, Sales)
----------------------
Choose the Department:
----------------------
1.IT
2.Sales
Option: 1
-------------------------------------
Sum of all salary for IT : 145000
Largest Salary: (46000, Anurag)
Minimum Salary: (16000, Preety)
Average Salary: 29000
No.of.Employees: 5
Contains ID-105: True
Using GroupBy, OrderBy & Key: 
Key: Female
        Hina,IT
        Sara,IT
        Pranaya,IT
Key: Male
        James,Sales
        Anurag,IT
        Manoj,Sales
        Sam,Sales
        Saurav,Sales
-------------------------------------
(101, Preety, 16000, IT)
(102, Priyanka, 15000, Sales)
(103, James, 50000, Sales)   
(104, Hina, 23000, IT)       
(105, Anurag, 46000, IT)     
(106, Sara, 25000, IT)       
(107, Pranaya, 35000, IT)    
(108, Manoj, 11000, Sales)   
(109, Sam, 45000, Sales)     
(110, Saurav, 25000, Sales)  
----------------------       
Choose the Department:       
----------------------       
1.IT
2.Sales
Option: 1
-------------------------------------
Sum of all salary for IT : 145000    
Largest Salary: (46000, Anurag)      
Minimum Salary: (16000, Preety)      
Average Salary: 29000
No.of.Employees: 5
Contains ID-105: True
Using GroupBy, OrderBy & Key:        
Key: Female
        Preety,IT
        Priyanka,Sales
        Hina,IT
        Sara,IT
        Pranaya,IT
Key: Male
        James,Sales
        Anurag,IT
        Manoj,Sales
        Sam,Sales
        Saurav,Sales
-------------------------------------

Conclusion

Thus in this example we have seen all the aggregate functions and their results which is simple and easy to understand. 

Thank you!

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