Csharp/C Sharp/LINQ/Take

Nested Take

 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
public class MainClass {
    public static void Main() {
        List<Customer> customers = GetCustomerList();
        var first3WAOrders = (
            from c in customers
            from o in c.Orders
            where c.Region == "R1"
            select new { c.CustomerId, o.Id, o.OrderDate })
            .Take(3);
        Console.WriteLine("First 3 orders in WA:");
        foreach (var order in first3WAOrders) {
            Console.WriteLine(order);
        }
    }
    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;
    }
}

Partitioning Operators: uses Take to generate a sequence of the first three elements of an integer array.

 
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 first3Numbers = numbers.Take(3);
        Console.WriteLine("First 3 numbers:");
        foreach (var n in first3Numbers) {
            Console.WriteLine(n);
        }
    }
}

Take and SelectMany

 
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"Aaa", "Art", "Buch", "Bushman", "Carter", "land"};
        IEnumerable<char> chars = presidents.Take(5).SelectMany(s => s.ToArray());
        foreach (char ch in chars)
            Console.WriteLine(ch);
    }
}

Take method

 
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
public class MainClass {
    public static void Main() {
        string[] presidents = {"A", "A", "B", "Bu", "Car", "land"};
        IEnumerable<string> items = presidents.Take(5);
        foreach (string item in items)
            Console.WriteLine(item);
    }
}

Take operator outputs the first x elements, discarding the rest

 
using System;
using System.Collections.Generic;
using System.Linq;
public class MainClass {
    public static void Main() {
        int[] numbers = { 10, 9, 8, 7, 6 };
        IEnumerable<int> firstThree = numbers.Take(3);     // { 10, 9, 8 }
    }
}

Use Take

 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
public class MainClass{
   public static void Main(){
       int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
       var query = numbers.Take(5);
       var query2 = numbers.Skip(5);
    }
}