Grouped Sum : Sum « LINQ « C# / CSharp Tutorial

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C# / CSharp Tutorial » LINQ » Sum 
22.70.6.Grouped Sum
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass {
    public static void Main() {

        List<Product> products = GetProductList();

        var categories =
           from p in products
           group p by p.Category into g
           select new Category = g.Key, TotalUnitsInStock = g.Sum(p => p.UnitsInStock) };

        Console.Write(categories);
    }
    static List<Product> GetProductList() {
        List<Product> empTree = new List<Product>();
        empTree.Add(new Product ProductName = "A", Category = "O", UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(200511), Id = });
        return empTree;
    }
    static List<Customer> GetCustomerList() {
        List<Product> empTree = new List<Product>();
        empTree.Add(new Product ProductName = "A", Category = "O", UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(200511), Id = });
        empTree.Add(new Product ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(200511), Id = });

        List<Customer> l = new List<Customer>();
        l.Add(new Customer CompanyName = "A", Region = "R1", UnitsInStock = 1, Orders = empTree, CustomerId = });
        l.Add(new Customer CompanyName = "B", Region = "R2", UnitsInStock = 2, Orders = empTree, CustomerId = });
        l.Add(new Customer CompanyName = "C", Region = "R3", UnitsInStock = 3, Orders = empTree, CustomerId = });
        l.Add(new Customer CompanyName = "D", Region = "R4", UnitsInStock = 4, Orders = empTree, CustomerId = });
        l.Add(new Customer CompanyName = "E", Region = "R5", UnitsInStock = 5, Orders = empTree, CustomerId = });
        return l;
    }

}
class Customer : IComparable<Customer> {
    public string CompanyName get; set; }
    public string Region get; set; }
    public List<Product> Orders get; set; }
    public int UnitsInStock get; set; }
    public int CustomerId get; set; }

    public override string ToString() {
        return String.Format("Id: {0}, Name: {1}, Region: {3}"this.CustomerId, this.CompanyName, this.Region);
    }
    int IComparable<Customer>.CompareTo(Customer other) {
        if (other == null)
            return 1;

        if (this.CustomerId > other.CustomerId)
            return 1;

        if (this.CustomerId < other.CustomerId)
            return -1;

        return 0;
    }
}
class Product : IComparable<Product> {
    public string ProductName get; set; }
    public string Category get; set; }
    public int UnitPrice get; set; }
    public int UnitsInStock get; set; }
    public int Total get; set; }
    public DateTime OrderDate get; set; }
    public int Id get; set; }

    public override string ToString() {
        return String.Format("Id: {0}, Name: {1} , Category: {3}"this.Id, this.ProductName, this.Category);
    }
    int IComparable<Product>.CompareTo(Product other) {
        if (other == null)
            return 1;
        if (this.Id > other.Id)
            return 1;

        if (this.Id < other.Id)
            return -1;

        return 0;
    }
}
22.70.Sum
22.70.1.use Linq Sum to sum an array
22.70.2.use Sum to find the total of all of the numbers in an integer array.
22.70.3.Sum with Projection
22.70.4.Sum with integers
22.70.5.Sum with object property
22.70.6.Grouped Sum
22.70.7.Numeric Aggregates: Sum
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