Csharp/CSharp Tutorial/LINQ/Min

Материал из .Net Framework эксперт
Версия от 15:18, 26 мая 2010; Admin (обсуждение | вклад) (1 версия)
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First Min Prototype

<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {

   public static void Main() {
       int[] myInts = new int[] { 974, 2, 7, 1374, 27, 54 };
       int minInt = myInts.Min();
       Console.WriteLine(minInt);
   }

}</source>

Grouped Min

<source lang="csharp">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.Min(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(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 2 });
       empTree.Add(new Product { ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 3 });
       empTree.Add(new Product { ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 4 });
       empTree.Add(new Product { ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 5 });
       empTree.Add(new Product { ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 6 });
       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(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "B", Category = "O", UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "C", Category = "O", UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "D", Category = "O", UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "E", Category = "O", UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       empTree.Add(new Product { ProductName = "F", Category = "O", UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
       List<Customer> l = new List<Customer>();
       l.Add(new Customer { CompanyName = "A", Region = "R1", UnitsInStock = 1, Orders = empTree, CustomerId = 0 });
       l.Add(new Customer { CompanyName = "B", Region = "R2", UnitsInStock = 2, Orders = empTree, CustomerId = 1 });
       l.Add(new Customer { CompanyName = "C", Region = "R3", UnitsInStock = 3, Orders = empTree, CustomerId = 2 });
       l.Add(new Customer { CompanyName = "D", Region = "R4", UnitsInStock = 4, Orders = empTree, CustomerId = 3 });
       l.Add(new Customer { CompanyName = "E", Region = "R5", UnitsInStock = 5, Orders = empTree, CustomerId = 4 });
       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.rupanyName, this.Region);
   }
   int IComparable<Customer>.rupareTo(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>.rupareTo(Product other) {
       if (other == null)
           return 1;
       if (this.Id > other.Id)
           return 1;
       if (this.Id < other.Id)
           return -1;
       return 0;
   }

}</source>

Min with object property

<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class Employee {

   public int birthYear;
   public string firstName;
   public string lastName;
   public static Employee[] GetEmployees() {
       Employee[] actors = new Employee[] {
       new Employee { birthYear = 1964, firstName = "Keanu", lastName = "Reeves" },
       new Employee { birthYear = 1968, firstName = "Owen", lastName = "Wilson" },
       new Employee { birthYear = 1960, firstName = "James", lastName = "Spader" },
       new Employee { birthYear = 1964, firstName = "Sandra", lastName = "Bullock" },
     };
       return (actors);
   }

} public class MainClass {

   public static void Main() {
       int oldestEmployeeAge = Employee.GetEmployees().Min(a => a.birthYear);
       Console.WriteLine(oldestEmployeeAge);
   }

}</source>

Min with string property value

<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class Employee {

   public int birthYear;
   public string firstName;
   public string lastName;
   public static Employee[] GetEmployees() {
       Employee[] actors = new Employee[] {
       new Employee { birthYear = 1964, firstName = "K", lastName = "R" },
       new Employee { birthYear = 1968, firstName = "O", lastName = "W" },
       new Employee { birthYear = 1960, firstName = "J", lastName = "S" },
       new Employee { birthYear = 1964, firstName = "S", lastName = "B" },
     };
       return (actors);
   }

} public class MainClass {

   public static void Main() {
       string firstAlphabetically = Employee.GetEmployees().Min(a => a.lastName);
       Console.WriteLine(firstAlphabetically);
   }

}</source>

Min with string value

<source lang="csharp">using System; using System.Linq; using System.Collections; using System.Collections.Generic; public class MainClass {

   public static void Main() {
       string[] presidents = {"G", "H", "a", "H", "over", "Jack"};
       string minName = presidents.Min();
       Console.WriteLine(minName);
   }

}</source>

Numeric Aggregates: Min

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text;

   class Program
   {
       static void Main(string[] args)
       {
           Random generator = new Random(0);
           int[] numbers = new int[1000];
           for (int i = 0; i < 1000; i++)
           {
               numbers[i] = generator.Next();
           }
           var queryResults = from n in numbers where n > 100 select n;
           Console.WriteLine("Min of Numbers > 100");
           Console.WriteLine(queryResults.Min());
       }
   }</source>

Using Min to get the length of the shortest word in a string array.

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {

   public static void Main() {
       string[] words = { "cherry", "apple", "blueberry" };
       int shortestWord = words.Min(w => w.Length);
       Console.WriteLine("The shortest word is {0} characters long.", shortestWord);
   }

}</source>

Using Min to get the lowest number in an integer array.

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Text; public class MainClass {

   public static void Main() {
       int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
       int minNum = numbers.Min();
       Console.WriteLine("The minimum number is {0}.", minNum);
   }

}</source>