в 15:31, 26 мая 2010

2010-05-26T15:31:18Z

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2010-05-26T11:38:37Z

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==GroupBy partitions a list of numbers by their remainder when divided by 5.==

<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 };
var numberGroups =
from n in numbers
group n by n % 5 into g
select new { Remainder = g.Key, Numbers = g };
foreach (var g in numberGroups) {
Console.WriteLine("Numbers with a remainder of {0} when divided by 5:", g.Remainder);
foreach (var n in g.Numbers) {
Console.WriteLine(n);
}
}
}
}
</source>

==Use Group By==

<source lang="csharp">
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Reflection;
public class MainClass{
public static void Main(){
var query = from m in typeof(double).GetMethods()
select m.Name;
var q = from m in typeof(double).GetMethods()
group m by m.Name into gb
select new {Name = gb.Key, Overloads = gb.Count()};
}
}
</source>

==uses group by to partition a list of each customer"s orders, first by year, and then by month.==

<source lang="csharp">
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
public static void Main() {
List<Customer> customers = GetCustomerList();
var customerOrderGroups =
from c in customers
select
new {
c.rupanyName,
YearGroups =
from o in c.Orders
group o by o.OrderDate.Year into yg
select
new {
Year = yg.Key,
MonthGroups =
from o in yg
group o by o.OrderDate.Month into mg
select new { Month = mg.Key, Orders = mg }
}
};
Console.Write(customerOrderGroups);
}
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>

==uses group by to partition a list of products by category.==

<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 orderGroups =
from p in products
group p by p.Category into g
select new { Category = g.Key, Products = g };
foreach (var s in orderGroups) {
Console.Write(s.Category);
}
}
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 = 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 });
return empTree;
}
}
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>

==uses GroupBy to partition trimmed elements of an array using a custom comparer==

<source lang="csharp">
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
public static void Main() {
string[] anagrams = { "from ", " salt", " earn ", " last ", " near ", " form " };
var orderGroups = anagrams.GroupBy(
w => w.Trim(),
a => a.ToUpper(),
new AnagramEqualityComparer()
);
foreach (var v in orderGroups) {
Console.WriteLine(v);
}
}
public class AnagramEqualityComparer : IEqualityComparer<string> {
public bool Equals(string x, string y) {
return getCanonicalString(x) == getCanonicalString(y);
}
public int GetHashCode(string obj) {
return getCanonicalString(obj).GetHashCode();
}
private string getCanonicalString(string word) {
char[] wordChars = word.ToCharArray();
Array.Sort<char>(wordChars);
return new string(wordChars);
}
}
}
</source>

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Csharp/C Sharp/LINQ/GroupBy - История изменений

в 15:31, 26 мая 2010

Admin: 1 версия