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

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C# / CSharp Tutorial » LINQ » Max 
22.54.7.Grouped Max
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, MostExpensivePrice = g.Max(p => p.UnitPrice) };

        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;
    }
}
22.54.Max
22.54.1.Max on int array
22.54.2.Max on String array
22.54.3.Max on object list
22.54.4.Max on Object list array
22.54.5.Using Max to get the highest number in an integer array.
22.54.6.uses Max to get the length of the longest word in a string array.
22.54.7.Grouped Max
22.54.8.Get the Min and max value from a query
22.54.9.Numeric Aggregates: max
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