Csharp/CSharp Tutorial/LINQ/Min
Содержание
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>
