Operation Comparison Matrix

Source

Side-by-side - C# LINQ vs python functional collections

deff:pass

LINQ - Filter Operators

linq1: Where - Simple 1

//c#staticvoidLinq1(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varlowNums=numbers.Where(n=>n<5);Console.WriteLine("Numbers < 5:");lowNums.ForEach(Console.WriteLine);}

#pythondeflinq1():numbers= [5,4,1,3,9,8,6,7,2,0]low_nums= (xforxinnumbersifx<5)print("Numbers < 5:")shared.printN(low_nums)

Output

Numbers < 5:41320

linq2: Where - Simple 2

//c#staticvoidLinq2(){varproducts=GetProductList();varsoldOutProducts=products.Where(p=>p.UnitsInStock==0);Console.WriteLine("Sold out products:");soldOutProducts.ForEach(x=>Console.WriteLine($"{x.ProductName} is sold out!"));}

#pythondeflinq2():products=shared.getProductList()sold_out_products= (xforxinproductsifx.UnitsInStock==0)print("Sold out products:")foriteminsold_out_products:print("%s is sold out!"%item.ProductName)

Output

Sold out products:Chef Anton's Gumbo Mix is sold out!Alice Mutton is sold out!Th�ringer Rostbratwurst is sold out!Gorgonzola Telino is sold out!Perth Pasties is sold out!

linq3: Where - Simple 3

//c#publicstaticvoidLinq3(){varproducts=GetProductList();varexpensiveInStockProducts=products.Where(p=>p.UnitsInStock>0&&p.UnitPrice>3.00M);Console.WriteLine("In-stock products that cost more than 3.00:");expensiveInStockProducts.ForEach(product=>Console.WriteLine($"{product.ProductName} is in stock and costs more than 3.00."));}

#pythondeflinq3():products=shared.getProductList()expensive_in_stock_products= (xforxinproductsifx.UnitsInStock>0andx.UnitPrice>3.0000)print("In-stock products that cost more than 3.00:")foriteminexpensive_in_stock_products:print("%s is in stock and costs more than 3.00."%item.ProductName)

Output

In-stock products that cost more than 3.00:Chai is in stock and costs more than 3.00.Chang is in stock and costs more than 3.00.Aniseed Syrup is in stock and costs more than 3.00....

linq4: Where - Drilldown

//c#staticvoidLinq4(){varcustomers=GetCustomerList();Console.WriteLine("Customers from Washington and their orders:");varwaCustomers=customers.Where(c=>c.Region=="WA");waCustomers.ForEach((customer)=>{Console.WriteLine($"Customer{customer.CustomerID}:{customer.CompanyName}");customer.Orders.ForEach((order)=>{Console.WriteLine($"  Order{order.OrderID}:{order.OrderDate}");});});}

#pythondeflinq4():customers=shared.getCustomerList()wa_customers= (xforxincustomersifx.Region=="WA")print("Customers from Washington and their orders:")forcustomerinwa_customers:print("Customer %s : %s"% (customer.CustomerID,customer.CompanyName))fororderincustomer.Orders:print("     Order %s: %s"% (order.OrderID,order.OrderDate))

Output

Customers from Washington and their orders:Customer LAZYK: Lazy K Kountry Store  Order 10482: 1997-03-21T00:00:00  Order 10545: 1997-05-22T00:00:00Customer TRAIH: Trail's Head Gourmet Provisioners  Order 10574: 1997-06-19T00:00:00  Order 10577: 1997-06-23T00:00:00  Order 10822: 1998-01-08T00:00:00...

linq5: Where - Indexed

//c#staticvoidLinq5(){vardigits=new[]{"zero","one","two","three","four","five","six","seven","eight","nine"};varshortDigits=digits.Where((digit,index)=>digit.Length<index);Console.WriteLine("Short digits:");shortDigits.ForEach(d=>Console.WriteLine($"The word{d} is shorter than its value."));}

#pythondeflinq5():digits= ["zero","one","two","three","four","five","six","seven","eight","nine"]index=0# Lambdas cant have multiple lines, so create a filter functiondeffilter_func(digit):nonlocalindexresult=len(digit)<indexindex+=1returnresultshort_digits=filter(filter_func,digits)print("Short digits:")fordinshort_digits:print("The word %s is shorter than its value."%d)

Output

Short digits:The word five is shorter than its value.The word six is shorter than its value.The word seven is shorter than its value.The word eight is shorter than its value.The word nine is shorter than its value.

LINQ - Projection Operators

linq6: Select - Simple 1

//c#staticvoidLinq6(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varnumsPlusOne=numbers.Select(n=>n+1);Console.WriteLine("Numbers + 1:");numsPlusOne.ForEach(Console.WriteLine);}

#pythondeflinq6():numbers= [5,4,1,3,9,8,6,7,2,0]nums_plus_one= (n+1forninnumbers)print("Numbers + 1:")shared.printN(nums_plus_one)

Output

Numbers + 1:65241097831

linq7: Select - Simple 2

//c#staticvoidLinq7(){varproducts=GetProductList();varproductNames=products.Select(p=>p.ProductName);Console.WriteLine("Product Names:");productNames.ForEach(Console.WriteLine);}

#pythondeflinq7():products=shared.getProductList()product_names= (p.ProductNameforpinproducts)print("Product Names:")shared.printS(product_names)

Output

Product Names:ChaiChangAniseed SyrupChef Anton's Cajun SeasoningChef Anton's Gumbo Mix...

linq8: Select - Transformation

//c#staticvoidLinq8(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varstrings=new[]{"zero","one","two","three","four","five","six","seven","eight","nine"};vartextNums=numbers.Select(n=>strings[n]);Console.WriteLine("Number strings:");textNums.ForEach(Console.WriteLine);}

#pythondeflinq8():numbers= [5,4,1,3,9,8,6,7,2,0]strings= ["zero","one","two","three","four","five","six","seven","eight","nine"]text_nums= (strings[n]forninnumbers)print("Number strings:")shared.printS(text_nums)

Output

Number strings:fivefouronethreenineeightsixseventwozero

linq9: Select - Anonymous Types 1

//c#staticvoidLinq9(){varwords=new[]{"aPPLE","BlUeBeRrY","cHeRry"};varupperLowerWords=words.Select(w=>new{Upper=w.ToUpper(),Lower=w.ToLower()});upperLowerWords.ForEach(ul=>Console.WriteLine($"Uppercase:{ul.Upper}, Lowercase:{ul.Lower}"));}

#pythondeflinq9():words= ["aPPLE","BlUeBeRrY","cHeRry"]upper_lower_words= (SimpleNamespace(Upper=w.upper(),Lower=w.lower())forwinwords)forwordinupper_lower_words:print("Uppercase: %s, Lowercase: %s"% (word.Upper,word.Lower))

Output

Uppercase: APPLE, Lowercase: appleUppercase: BLUEBERRY, Lowercase: blueberryUppercase: CHERRY, Lowercase: cherry

linq10: Select - Anonymous Types 2

//c#staticvoidLinq10(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varstrings=new[]{"zero","one","two","three","four","five","six","seven","eight","nine"};vardigitOddEvens=numbers.Select(n=>new{Digit=strings[n],Even=(n%2==0)});digitOddEvens.ForEach(d=>Console.WriteLine($"The digit{d.Digit} is{(d.Even?"even":"odd")}."));}

#pythondeflinq10():numbers= [5,4,1,3,9,8,6,7,2,0]strings= ["zero","one","two","three","four","five","six","seven","eight","nine"]digit_odd_evens= (SimpleNamespace(Digit=strings[n],Even=(n%2==0))forninnumbers)fordindigit_odd_evens:print("The digit %s is %s"% (d.Digit,'even'ifd.Evenelse'odd'))

Output

The digit five is odd.The digit four is even.The digit one is odd.The digit three is odd.The digit nine is odd.The digit eight is even.The digit six is even.The digit seven is odd.The digit two is even.The digit zero is even.

linq11: Select - Anonymous Types 3

//c#staticvoidLinq11(){varproducts=GetProductList();varproductInfos=products.Select(p=>new{p.ProductName,p.Category,Price=p.UnitPrice});Console.WriteLine("Product Info:");productInfos.ForEach(productInfo=>Console.WriteLine($"{productInfo.ProductName} is in the category{productInfo.Category} and costs{productInfo.Price} per unit."));}

#pythondeflinq11():products=shared.getProductList()product_info= (SimpleNamespace(ProductName=p.ProductName,Category=p.Category,Price=p.UnitPrice)forpinproducts)print("Product Info:")forproductinproduct_info:print("%s is in the category %s and costs %.2f per unit."% (product.ProductName,product.Category,product.Price))

Output

Product Info:Chai is in the category Beverages and costs 18.0 per unit.Chang is in the category Beverages and costs 19.0 per unit.Aniseed Syrup is in the category Condiments and costs 10.0 per unit....

linq12: Select - Indexed

//c#staticvoidLinq12(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varnumsInPlace=numbers.Select((num,index)=>new{Num=num,InPlace=(num==index)});Console.WriteLine("Number: In-place?");numsInPlace.ForEach(n=>Console.WriteLine($"{n.Num}:{n.InPlace}"));}

#pythondeflinq12():numbers= [5,4,1,3,9,8,6,7,2,0]index=0defdigit_equals_index(digit):nonlocalindexresult=digit==indexindex+=1returnresultnums_in_place= (SimpleNamespace(Num=num,InPlace=digit_equals_index(num))fornuminnumbers)print("Number: In-place?")forninnums_in_place:print("%d: %s"% (n.Num,n.InPlace))

Output

Number: In-place?5: False4: False1: False3: True9: False8: False6: True7: True2: False0: False

linq13: Select - Filtered

//c#staticvoidLinq13(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};vardigits=new[]{"zero","one","two","three","four","five","six","seven","eight","nine"};varlowNums=numbers.Where(n=>n<5).Select(n=>digits[n]);Console.WriteLine("Numbers < 5:");lowNums.ForEach(Console.WriteLine);}

#pythondeflinq13():numbers= [5,4,1,3,9,8,6,7,2,0]digits= ["zero","one","two","three","four","five","six","seven","eight","nine"]result= (digits[n]forninnumbersifn<5)print("Numbers < 5:")shared.printS(result)

Output

Numbers < 5:fouronethreetwozero

linq14: SelectMany - Compound from 1

//c#staticvoidLinq14(){varnumbersA=new[]{0,2,4,5,6,8,9};varnumbersB=new[]{1,3,5,7,8};varpairs=numbersA.SelectMany(a=>numbersB,(a,b)=>new{a,b}).Where(x=>x.a<x.b);Console.WriteLine("Pairs where a < b:");pairs.ForEach(pair=>Console.WriteLine("{0} is less than {1}",pair.a,pair.b));}

#pythondeflinq14():numbers_a= [0,2,4,5,6,8,9]numbers_b= [1,3,5,7,8]pairs= ((a,b)forainnumbers_aforbinnumbers_bif (a<b))print("Pairs where a < b:")forpinpairs:print("%d is less than %d"% (p[0],p[1]))

Output

Pairs where a < b:0 is less than 10 is less than 30 is less than 50 is less than 70 is less than 82 is less than 32 is less than 52 is less than 72 is less than 84 is less than 54 is less than 74 is less than 85 is less than 75 is less than 86 is less than 76 is less than 8

linq15: SelectMany - Compound from 2

//c#staticvoidLinq15(){varcustomers=GetCustomerList();varorders=customers.SelectMany(customer=>customer.Orders,(customer,order)=>new{customer,order}).Where(x=>x.order.Total<500.00M).Select(x=>new{x.customer.CustomerID,x.order.OrderID,x.order.Total});ObjectDumper.Write(orders);}

#pythondeflinq15():customers=shared.getCustomerList()orders_less_than_500= ((customer,order)forcustomerincustomersfororderincustomer.Ordersiforder.Total<500.00)orders= (SimpleNamespace(customer_id=x[0].CustomerID,order_id=x[1].OrderID,total=x[1].Total)forxinorders_less_than_500)shared.print_namespace(orders)

Output

{CustomerId: ALFKI, OrderId: 10702, Total: 330.0}{CustomerId: ALFKI, OrderId: 10952, Total: 471.2}{CustomerId: ANATR, OrderId: 10308, Total: 88.8}{CustomerId: ANATR, OrderId: 10625, Total: 479.75}...

linq16: SelectMany - Compound from 3

//c#staticvoidLinq16(){varcustomers=GetCustomerList();varorders=customers.SelectMany(customer=>customer.Orders,(customer,order)=>new{customer,order}).Where(x=>x.order.OrderDate>=newDateTime(1998,1,1)).Select(x=>new{x.customer.CustomerID,x.order.OrderID,x.order.OrderDate});ObjectDumper.Write(orders);}

#pythondeflinq16():customers=shared.getCustomerList()the_date=datetime.datetime(1998,1,1)order_greater_than_date= ((customer,order)forcustomerincustomersfororderincustomer.Ordersiforder.OrderDate>the_date)orders= (SimpleNamespace(customer_id=x[0].CustomerID,order_id=x[1].OrderID,orderDate=x[1].OrderDate)forxinorder_greater_than_date)shared.print_namespace(orders)

Output

{CustomerId: ALFKI, OrderId: 10835, OrderDate: 1998-01-15 00:00:00.000}{CustomerId: ALFKI, OrderId: 10952, OrderDate: 1998-03-16 00:00:00.000}{CustomerId: ALFKI, OrderId: 11011, OrderDate: 1998-04-09 00:00:00.000}{CustomerId: ANATR, OrderId: 10926, OrderDate: 1998-03-04 00:00:00.000}{CustomerId: ANTON, OrderId: 10856, OrderDate: 1998-01-28 00:00:00.000}...

linq17: SelectMany - from Assignment

//c#staticvoidLinq17(){varcustomers=GetCustomerList();varorders=customers.SelectMany(customer=>customer.Orders,(customer,order)=>new{customer,order}).Where(x=>x.order.Total>=2000.00M).Select(x=>new{x.customer.CustomerID,x.order.OrderID,x.order.Total});ObjectDumper.Write(orders);}

#pythondeflinq17():customers=shared.getCustomerList()orders_greater_than_2000= ((customer,order)forcustomerincustomersfororderincustomer.Ordersiforder.Total>2000.00)orders= (SimpleNamespace(customer_id=x[0].CustomerID,order_id=x[1].OrderID,total=x[1].Total)forxinorders_greater_than_2000)shared.print_namespace(orders)

Output

(customer_id='ANTON', order_id=10573, total=2082.0)(customer_id='AROUT', order_id=10558, total=2142.9)(customer_id='AROUT', order_id=10953, total=4441.25)(customer_id='BERGS', order_id=10384, total=2222.4)(customer_id='BERGS', order_id=10524, total=3192.65)...

linq18: SelectMany - Multiple from

//c#staticvoidLinq18(){varcustomers=GetCustomerList();varorders=customers.Where(c=>c.Region=="WA").SelectMany(customer=>customer.Orders,(customer,order)=>new{customer,order}).Where(x=>x.order.OrderDate>=cutoffDate).Select(x=>new{x.customer.CustomerID,x.customer.Region,x.order.OrderID});ObjectDumper.Write(orders);}

#pythondeflinq18():customers=shared.getCustomerList()the_date=datetime.datetime(1998,1,1)order_greater_than_date= ((customer,order)forcustomerincustomersfororderincustomer.Ordersiforder.OrderDate>the_date)orders= (SimpleNamespace(customer_id=x[0].CustomerID,order_id=x[1].OrderID,orderDate=x[1].OrderDate)forxinorder_greater_than_date)shared.print_namespace(orders)

Output

(customer_id='ALFKI', orderDate=datetime.datetime(1998, 1, 15, 0, 0), order_id=10835)(customer_id='ALFKI', orderDate=datetime.datetime(1998, 3, 16, 0, 0), order_id=10952)(customer_id='ALFKI', orderDate=datetime.datetime(1998, 4, 9, 0, 0), order_id=11011)(customer_id='ANATR', orderDate=datetime.datetime(1998, 3, 4, 0, 0), order_id=10926)(customer_id='ANTON', orderDate=datetime.datetime(1998, 1, 28, 0, 0), order_id=10856)...

linq19: SelectMany - Indexed

//c#publicvoidLinq19(){varcustomers=GetCustomerList();varcustomerOrders=customers.SelectMany((cust,custIndex)=>cust.Orders.Select(o=>$"Customer #{custIndex+1}) has an order with OrderID{o.OrderID}"));ObjectDumper.Write(customerOrders);}

#pythondeflinq19():customers=shared.getCustomerList()index=0defget_cust_index_func():nonlocalindexindex+=1returnindexcustomer_orders= ((cust,get_cust_index_func(),order)forcustincustomersfororderincust.Orders)fortripletincustomer_orders:print("Customer #%d has an order with OrderID %d"% (triplet[1],triplet[2].OrderID))

Output

Customer #1 has an order with OrderID 10643Customer #1 has an order with OrderID 10692Customer #1 has an order with OrderID 10702Customer #1 has an order with OrderID 10835Customer #1 has an order with OrderID 10952Customer #1 has an order with OrderID 11011Customer #2 has an order with OrderID 10308Customer #2 has an order with OrderID 10625Customer #2 has an order with OrderID 10759Customer #2 has an order with OrderID 10926...

LINQ - Partitioning Operators

linq20: Take - Simple

//c#staticvoidLinq20(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varfirst3Numbers=numbers.Take(3);Console.WriteLine("First 3 numbers:");first3Numbers.ForEach(Console.WriteLine);}

#pythondeflinq20():numbers= [5,4,1,3,9,8,6,7,2,0]first3_numbers=numbers[:3]print("First 3 numbers:")shared.printN(first3_numbers)

Output

First 3 numbers:541

linq21: Take - Nested

//c#staticvoidLinq21(){varcustomers=GetCustomerList();varfirst3WAOrders=customers.Where(c=>c.Region=="WA").SelectMany(customer=>customer.Orders,(customer,order)=>new{customer,order}).Select(x=>new{x.customer.CustomerID,x.order.OrderID,x.order.OrderDate}).Take(3);Console.WriteLine("First 3 orders in WA:");first3WAOrders.ForEach(ObjectDumper.Write);}

#pythondeflinq21():customers=shared.getCustomerList()order_greater_than_date= ((cust,order)forcustincustomersfororderincust.Ordersifcust.Region=="WA")orders= [SimpleNamespace(customer_id=x[0].CustomerID,order_id=x[1].OrderID,orderDate=x[1].OrderDate)forxinorder_greater_than_date]first_3_orders=orders[:3]print("First 3 orders in WA:")shared.print_namespace(first_3_orders)

Output

First 3 orders in WA:(customer_id='LAZYK', orderDate=datetime.datetime(1997, 3, 21, 0, 0), order_id=10482)(customer_id='LAZYK', orderDate=datetime.datetime(1997, 5, 22, 0, 0), order_id=10545)(customer_id='TRAIH', orderDate=datetime.datetime(1997, 6, 19, 0, 0), order_id=10574)

linq22: Skip - Simple

//c#staticvoidLinq22(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varallButFirst4Numbers=numbers.Skip(4);Console.WriteLine("All but first 4 numbers:");allButFirst4Numbers.ForEach(Console.WriteLine);}

#pythondeflinq22():numbers= [5,4,1,3,9,8,6,7,2,0]all_but_first4_numbers=numbers[4:]print("All but first 4 numbers:")shared.printN(all_but_first4_numbers)

Output

All but first 4 numbers:986720

linq23: Skip - Nested

//c#staticvoidLinq23(){varcustomers=GetCustomerList();varwaOrders=customers.Where(c=>c.Region=="WA").SelectMany(customer=>customer.Orders,(customer,order)=>new{customer,order}).Select(x=>new{x.customer.CustomerID,x.order.OrderID,x.order.OrderDate});varallButFirst2Orders=waOrders.Skip(2);Console.WriteLine("All but first 2 orders in WA:");ObjectDumper.Write(allButFirst2Orders);}

#pythondeflinq23():customers=shared.getCustomerList()wa_customers=filter(lambdac:c.Region=="WA",customers)wa_customer_orders=functions.select_many(wa_customers,"Orders")customer_orders=map(lambdax:SimpleNamespace(customer_id=x.item_a.CustomerID,order_id=x.item_b.OrderID,order_date=x.item_b.OrderDate),wa_customer_orders)all_but_first2=list(customer_orders)[2:]print("All but first 2 orders in WA:")shared.print_namespace(all_but_first2)

Output

All but first 2 orders in WA:(customer_id='TRAIH', orderDate=datetime.datetime(1997, 6, 19, 0, 0), order_id=10574)(customer_id='TRAIH', orderDate=datetime.datetime(1997, 6, 23, 0, 0), order_id=10577)(customer_id='TRAIH', orderDate=datetime.datetime(1998, 1, 8, 0, 0), order_id=10822)(customer_id='WHITC', orderDate=datetime.datetime(1996, 7, 31, 0, 0), order_id=10269)(customer_id='WHITC', orderDate=datetime.datetime(1996, 11, 1, 0, 0), order_id=10344)(customer_id='WHITC', orderDate=datetime.datetime(1997, 3, 10, 0, 0), order_id=10469)(customer_id='WHITC', orderDate=datetime.datetime(1997, 3, 24, 0, 0), order_id=10483)(customer_id='WHITC', orderDate=datetime.datetime(1997, 4, 11, 0, 0), order_id=10504)(customer_id='WHITC', orderDate=datetime.datetime(1997, 7, 11, 0, 0), order_id=10596)(customer_id='WHITC', orderDate=datetime.datetime(1997, 10, 6, 0, 0), order_id=10693)(customer_id='WHITC', orderDate=datetime.datetime(1997, 10, 8, 0, 0), order_id=10696)(customer_id='WHITC', orderDate=datetime.datetime(1997, 10, 30, 0, 0), order_id=10723)(customer_id='WHITC', orderDate=datetime.datetime(1997, 11, 13, 0, 0), order_id=10740)(customer_id='WHITC', orderDate=datetime.datetime(1998, 1, 30, 0, 0), order_id=10861)(customer_id='WHITC', orderDate=datetime.datetime(1998, 2, 24, 0, 0), order_id=10904)(customer_id='WHITC', orderDate=datetime.datetime(1998, 4, 17, 0, 0), order_id=11032)(customer_id='WHITC', orderDate=datetime.datetime(1998, 5, 1, 0, 0), order_id=11066)

linq24: TakeWhile - Simple

//c#staticvoidLinq24(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varfirstNumbersLessThan6=numbers.TakeWhile(n=>n<6);Console.WriteLine("First numbers less than 6:");firstNumbersLessThan6.ForEach(Console.WriteLine);}

#pythondeflinq24():numbers= [5,4,1,3,9,8,6,7,2,0]first_numbers_less_than6=takewhile(lambdax:x<6,numbers)print("First numbers less than 6:")shared.printN(first_numbers_less_than6)

Output

First numbers less than 6:5413

linq25: TakeWhile - Indexed

//c#staticvoidLinq25(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varfirstSmallNumbers=numbers.TakeWhile((n,index)=>n>=index);Console.WriteLine("First numbers not less than their position:");firstSmallNumbers.ForEach(Console.WriteLine);}

#pythondeflinq25():numbers= [5,4,1,3,9,8,6,7,2,0]index=0defdigit_greater_equal_to_index(digit):nonlocalindexresult=digit>=indexindex+=1returnresultfirst_small_numbers=takewhile(digit_greater_equal_to_index,numbers)print("First numbers not less than their position:")shared.printN(first_small_numbers)

Output

First numbers not less than their position:54

linq26: SkipWhile - Simple

//c#staticvoidLinq26(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varallButFirst3Numbers=numbers.SkipWhile(n=>n%3!=0);Console.WriteLine("All elements starting from first element divisible by 3:");allButFirst3Numbers.ForEach(Console.WriteLine);}

#pythondeflinq26():numbers= [5,4,1,3,9,8,6,7,2,0]all_but_first3_numbers=dropwhile(lambdan:n%3!=0,numbers)print("All elements starting from first element divisible by 3:")shared.printN(all_but_first3_numbers)

Output

All elements starting from first element divisible by 3:3986720

linq27: SkipWhile - Indexed

//c#staticvoidLinq27(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varlaterNumbers=numbers.SkipWhile((n,index)=>n>=index);Console.WriteLine("All elements starting from first element less than its position:");laterNumbers.ForEach(Console.WriteLine);}

#pythondeflinq27():numbers= [5,4,1,3,9,8,6,7,2,0]index=0defdigit_greater_equal_to_index(digit):nonlocalindexresult=digit>=indexindex+=1returnresultlater_numbers=dropwhile(digit_greater_equal_to_index,numbers)print("All elements starting from first element less than its position:")shared.printN(later_numbers)

Output

All elements starting from first element less than its position:13986720

LINQ - Ordering Operators

linq28: OrderBy - Simple 1

//c#staticvoidLinq28(){varwords=new[]{"cherry","apple","blueberry"};varsortedWords=words.OrderBy(w=>w);Console.WriteLine("The sorted list of words:");sortedWords.ForEach(Console.WriteLine);}

#pythondeflinq28():words= ["cherry","apple","blueberry"]sorted_words=sorted(words)print("The sorted list of words:")shared.printS(sorted_words)

Output

The sorted list of words:appleblueberrycherry

linq29: OrderBy - Simple 2

//c#staticvoidLinq29(){varwords=new[]{"cherry","apple","blueberry"};varsortedWords=words.OrderBy(w=>w.Length);Console.WriteLine("The sorted list of words (by length):");sortedWords.ForEach(Console.WriteLine);}

#pythondeflinq29():words= ["cherry","apple","blueberry"]sorted_words=sorted(words,key=lambdax:len(x))print("The sorted list of words (by length):")shared.printS(sorted_words)

Output

The sorted list of words (by length):applecherryblueberry

linq30: OrderBy - Simple 3

//c#staticvoidLinq30(){varproducts=GetProductList();varsortedProducts=products.OrderBy(p=>p.ProductName);ObjectDumper.Write(sortedProducts);}

#pythondeflinq30():products=shared.getProductList()sorted_products=sorted(products,key=lambdap:p.ProductName)shared.print_namespace(sorted_products)

Output

{productId: 17, productName: Alice Mutton, category: Meat/Poultry, unitPrice: 39.0, unitsInStock: 0}{productId: 3, productName: Aniseed Syrup, category: Condiments, unitPrice: 10.0, unitsInStock: 13}{productId: 40, productName: Boston Crab Meat, category: Seafood, unitPrice: 18.4, unitsInStock: 123}{productId: 60, productName: Camembert Pierrot, category: Dairy Products, unitPrice: 34.0, unitsInStock: 19}{productId: 18, productName: Carnarvon Tigers, category: Seafood, unitPrice: 62.5, unitsInStock: 42}...

linq31: OrderBy - Comparer

//c#staticvoidLinq31(){varwords=new[]{"aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"};varsortedWords=words.OrderBy(a=>a,StringComparer.CurrentCultureIgnoreCase);ObjectDumper.Write(sortedWords);}

#pythondeflinq31():words= ["aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"]sorted_words=sorted(words,key=lambdas:s.casefold())shared.printS(sorted_words)

Output

AbAcUsaPPLEBlUeBeRrYbRaNcHcHeRryClOvEr

linq32: OrderByDescending - Simple 1

//c#staticvoidLinq32(){vardoubles=new[]{1.7,2.3,1.9,4.1,2.9};varsortedDoubles=doubles.OrderByDescending(d=>d);Console.WriteLine("The doubles from highest to lowest:");sortedDoubles.ForEach(Console.WriteLine);}

#pythondeflinq32():doubles= [1.7,2.3,1.9,4.1,2.9]sorted_doubles=sorted(doubles,reverse=True)print("The doubles from highest to lowest:")shared.printN(sorted_doubles)

Output

The doubles from highest to lowest:4.12.92.31.91.7

linq33: OrderByDescending - Simple 2

//c#staticvoidLinq33(){varproducts=GetProductList();varsortedProducts=products.OrderByDescending(p=>p.UnitsInStock);ObjectDumper.Write(sortedProducts);}

#pythondeflinq33():products=shared.getProductList()sorted_products=sorted(products,key=lambdap:p.UnitsInStock,reverse=True)shared.print_namespace(sorted_products)

Output

{productId: 75, productName: Rh�nbr�u Klosterbier, category: Beverages, unitPrice: 7.75, unitsInStock: 125}{productId: 40, productName: Boston Crab Meat, category: Seafood, unitPrice: 18.4, unitsInStock: 123}{productId: 6, productName: Grandma's Boysenberry Spread, category: Condiments, unitPrice: 25.0, unitsInStock: 120}{productId: 55, productName: P�t� chinois, category: Meat/Poultry, unitPrice: 24.0, unitsInStock: 115}{productId: 61, productName: Sirop d'�rable, category: Condiments, unitPrice: 28.5, unitsInStock: 113}...

linq34: OrderByDescending - Comparer

//c#staticvoidLinq34(){varwords=new[]{"aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"};varsortedWords=words.OrderByDescending(a=>a,StringComparer.CurrentCultureIgnoreCase);ObjectDumper.Write(sortedWords);}

#pythondeflinq34():words= ["aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"]sorted_words=sorted(words,key=lambdas:s.casefold(),reverse=True)shared.print_namespace(sorted_words)

Output

ClOvErcHeRrybRaNcHBlUeBeRrYaPPLEAbAcUs

linq35: ThenBy - Simple

//c#staticvoidLinq35(){vardigits=new[]{"zero","one","two","three","four","five","six","seven","eight","nine"};varsortedDigits=digits.OrderBy(d=>d.Length).ThenBy(d=>d);Console.WriteLine("Sorted digits:");sortedDigits.ForEach(Console.WriteLine);}

#pythondeflinq35():digits= ["zero","one","two","three","four","five","six","seven","eight","nine"]sorted_digits=sorted(digits,key=lambdadigit: (len(digit),digit))print("Sorted digits:")shared.printS(sorted_digits)

Output

Sorted digits:onesixtwofivefourninezeroeightseventhree

linq36: ThenBy - Comparer

//c#staticvoidLinq36(){varwords=new[]{"aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"};varsortedWords=words.OrderBy(a=>a.Length).ThenBy(a=>a,StringComparer.CurrentCultureIgnoreCase);ObjectDumper.Write(sortedWords);}

#pythondeflinq36():words= ["aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"]sorted_words=sorted(words,key=lambdaword: (len(word),word.casefold()))shared.printS(sorted_words)

Output

aPPLEAbAcUsbRaNcHcHeRryClOvErBlUeBeRrY

linq37: ThenByDescending - Simple

//c#publicvoidLinq37(){List<Product>products=GetProductList();varsortedProducts=products.OrderBy(p=>p.Category).ThenByDescending(p=>p.UnitPrice);ObjectDumper.Write(sortedProducts);}

#pythondeflinq37():products=shared.getProductList()# negate secondary sort because its a number for reverse ordersorted_products=sorted(products,key=lambdaproduct: (product.Category,-product.UnitPrice))shared.print_namespace(sorted_products)

Output

{productId: 38, productName: C�te de Blaye, category: Beverages, unitPrice: 263.5, unitsInStock: 17}{productId: 43, productName: Ipoh Coffee, category: Beverages, unitPrice: 46.0, unitsInStock: 17}{productId: 2, productName: Chang, category: Beverages, unitPrice: 19.0, unitsInStock: 17}{productId: 76, productName: Lakkalik��ri, category: Beverages, unitPrice: 18.0, unitsInStock: 57}{productId: 39, productName: Chartreuse verte, category: Beverages, unitPrice: 18.0, unitsInStock: 69}{productId: 1, productName: Chai, category: Beverages, unitPrice: 18.0, unitsInStock: 39}{productId: 35, productName: Steeleye Stout, category: Beverages, unitPrice: 18.0, unitsInStock: 20}{productId: 70, productName: Outback Lager, category: Beverages, unitPrice: 15.0, unitsInStock: 15}{productId: 34, productName: Sasquatch Ale, category: Beverages, unitPrice: 14.0, unitsInStock: 111}...

linq38: ThenByDescending - Comparer

//c#staticvoidLinq38(){varwords=new[]{"aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"};varsortedWords=words.OrderBy(a=>a.Length).ThenByDescending(a=>a,StringComparer.CurrentCultureIgnoreCase);ObjectDumper.Write(sortedWords);}

#pythondeflinq38():words= ["aPPLE","AbAcUs","bRaNcH","BlUeBeRrY","ClOvEr","cHeRry"]# two pass sort, sort by least significant firstsorted_words=sorted(words,key=lambdaword:word.casefold(),reverse=True)sorted_words=sorted(sorted_words,key=lambdaword:len(word))shared.printS(sorted_words)

Output

aPPLEClOvErcHeRrybRaNcHAbAcUsBlUeBeRrY

linq39: Reverse

//c#staticvoidLinq39(){vardigits=new[]{"zero","one","two","three","four","five","six","seven","eight","nine"};varreversedIDigits=digits.Where(d=>d[1]=='i').Reverse();Console.WriteLine("A backwards list of the digits with a second character of 'i':");reversedIDigits.ForEach(Console.WriteLine);}

#pythondeflinq39():digits= ["zero","one","two","three","four","five","six","seven","eight","nine"]reversed_i_digits=reversed(list(filter(lambdadigit:digit[1]=="i",digits)))print("A backwards list of the digits with a second character of 'i':")shared.printS(reversed_i_digits)

Output

A backwards list of the digits with a second character of 'i':nineeightsixfive

LINQ - Grouping Operators

linq40: GroupBy - Simple 1

//c#staticvoidLinq40(){varnumbers=new[]{5,4,1,3,9,8,6,7,2,0};varnumberGroups=numbers.GroupBy(n=>n%5).Select(x=>new{Remainder=x.Key,Numbers=x});numberGroups.ForEach((g)=>{Console.WriteLine("Numbers with a remainder of {0} when divided by 5:",g.Remainder);g.Numbers.ForEach(Console.WriteLine);});}

#pythondeflinq40():numbers= [5,4,1,3,9,8,6,7,2,0]# First create a record of numbers and their modulus of 5number_remainders=map(lambdan:SimpleNamespace(Number=n,Remainder=n%5),numbers)# Group By only works on sorted lists, so sort by both fieldssorted_by_reminder=sorted(number_remainders,key=lambdax: (x.Remainder,x.Number))remainder_groups=groupby(sorted_by_reminder,key=lambdanr:nr.Remainder)forkey,itemsinremainder_groups:print("Numbers with a remainder of %d when divided by 5:"%key)foriteminitems:print(item.Number)

Output

Numbers with a remainder of 0 when divided by 5:50Numbers with a remainder of 1 when divided by 5:16Numbers with a remainder of 2 when divided by 5:72Numbers with a remainder of 3 when divided by 5:38Numbers with a remainder of 4 when divided by 5:49

linq41: GroupBy - Simple 2

//c#staticvoidLinq41(){varwords=new[]{"blueberry","chimpanzee","abacus","banana","apple","cheese"};varwordGroups=words.GroupBy(w=>w[0]).Select(g=>new{FirstLetter=g.Key,Words=g});wordGroups.ForEach((g)=>{Console.WriteLine($"Words that start with the letter '{g.FirstLetter}':");g.Words.ForEach(Console.WriteLine);});}

#pythondeflinq41():words= ["blueberry","chimpanzee","abacus","banana","apple","cheese"]first_letter_words=map(lambdaw:SimpleNamespace(Letter=w[0],Word=w),words)# Group By only works on sorted lists, so sort by both fieldssorted_letter_words=sorted(first_letter_words,key=lambdax: (x.Word,x.Letter))letter_groups=groupby(sorted_letter_words,key=lambdanr:nr.Letter)forkey,itemsinletter_groups:print("Words that start with the letter '%s':"%key)foriteminitems:print(item.Word)

Output

Words that start with the letter 'a':abacusappleWords that start with the letter 'b':bananablueberryWords that start with the letter 'c':cheesechimpanzee

linq42: GroupBy - Simple 3

//c#staticvoidLinq42(){varproducts=GetProductList();varorderGroups=products.GroupBy(p=>p.Category).Select(g=>new{Category=g.Key,Products=g});ObjectDumper.Write(orderGroups,1);}

#pythondeflinq42():products=shared.getProductList()sorted_by_category=sorted(products,key=lambdap:p.Category)order_groups=groupby(sorted_by_category,key=lambdap:p.Category)forkey,itemsinorder_groups:print("Products in the category '%s':"%key)print(list(items))

Output

Products in the category 'Beverages':[{productId: 1, productName: Chai, category: Beverages, unitPrice: 18.00, unitsInStock: 39}, {productId: 2, productName: Products in the category 'Condiments':[{productId: 3, productName: Aniseed Syrup, category: Condiments, unitPrice: 10.00, unitsInStock: 13}, {productId: 4, Products in the category 'Confections':[{productId: 16, productName: Pavlova, category: Confections, unitPrice: 17.45, unitsInStock: 29}, {productId: 19, Products in the category 'Dairy Products':[{productId: 11, productName: Queso Cabrales, category: Dairy Products, unitPrice: 21.00, unitsInStock: 22}, {productId: Products in the category 'Grains/Cereals':[{productId: 22, productName: Gustaf's Knäckebröd, category: Grains/Cereals, unitPrice: 21.00, unitsInStock: 104}, Products in the category 'Meat/Poultry':[{productId: 9, productName: Mishi Kobe Niku, category: Meat/Poultry, unitPrice: 97.00, unitsInStock: 29}, {productId: 17,Products in the category 'Produce':[{productId: 7, productName: Uncle Bob's Organic Dried Pears, category: Produce, unitPrice: 30.00, unitsInStock: 15}, Products in the category 'Seafood':[{productId: 10, productName: Ikura, category: Seafood, unitPrice: 31.00, unitsInStock: 31}, {productId: 13, productName:

linq43: GroupBy - Nested

//c#publicvoidLinq43(){varcustomers=GetCustomerList();varcustomerOrderGroups=customers.Select(c=>new{c.CompanyName,YearGroups=(c.Orders.GroupBy(y=>y.OrderDate.Year).Select(YearGroup=>new{Year=YearGroup.Key,MonthGroups=(YearGroup.GroupBy(m=>m.OrderDate.Month).Select(MonthGroup=>new{Month=MonthGroup.Key,Orders=MonthGroup}))}))});ObjectDumper.Write(customerOrderGroups,3);}

#pythondeflinq43():pass

Output

{CompanyName: Alfreds Futterkiste, YearGroups: {{Year: 1997, MonthGroups: {{Month: 8, Orders: {{orderId: 10643, orderDate: 1997-08-25 00:00:00.000, total: 814.5}}}, {Month: 10, Orders: {{orderId: 10692, orderDate: 1997-10-03 00:00:00.000, total: 878.0}, {orderId: 10702, orderDate: 1997-10-13 00:00:00.000, total: 330.0}}}}}, {Year: 1998, MonthGroups: {{Month: 1, Orders: {{orderId: 10835, orderDate: 1998-01-15 00:00:00.000, total: 845.8}}}, {Month: 3, Orders: {{orderId: 10952, orderDate: 1998-03-16 00:00:00.000, total: 471.2}}}, {Month: 4, Orders: {{orderId: 11011, orderDate: 1998-04-09 00:00:00.000, total: 933.5}}}}}}}{CompanyName: Ana Trujillo Emparedados y helados, YearGroups: {{Year: 1996, MonthGroups: {{Month: 9, Orders: {{orderId: 10308, orderDate: 1996-09-18 00:00:00.000, total: 88.8}}}}}, {Year: 1997, MonthGroups: {{Month: 8, Orders: {{orderId: 10625, orderDate: 1997-08-08 00:00:00.000, total: 479.75}}}, {Month: 11, Orders: {{orderId: 10759, orderDate: 1997-11-28 00:00:00.000, total: 320.0}}}}}, {Year: 1998, MonthGroups: {{Month: 3, Orders: {{orderId: 10926, orderDate: 1998-03-04 00:00:00.000, total: 514.4}}}}}}}

LINQ - Set Operators

linq46: Distinct - 1

//c#staticvoidLinq46(){int[]factorsOf300={2,2,3,5,5};varuniqueFactors=factorsOf300.Distinct();Console.WriteLine("Prime factors of 300:");uniqueFactors.ForEach(Console.WriteLine);}

#pythondeflinq46():factors_of300= [2,2,3,5,5]unique_factors=set(factors_of300)print("Prime factors of 300:")shared.printN(unique_factors)

Output

Prime factors of 300:235

linq47: Distinct - 2

//c#staticvoidLinq47(){varproducts=GetProductList();varcategoryNames=products.Select(p=>p.Category).Distinct();Console.WriteLine("Category names:");categoryNames.ForEach(Console.WriteLine);}

#pythondeflinq47():products=shared.getProductList()category_names= {p.Categoryforpinproducts}print("Category names:")shared.printS(category_names)

Output

Category names:BeveragesDairy ProductsCondimentsMeat/PoultryProduceSeafoodGrains/CerealsConfections

linq48: Union - 1

//c#staticvoidLinq48(){int[]numbersA={0,2,4,5,6,8,9};int[]numbersB={1,3,5,7,8};varuniqueNumbers=numbersA.Union(numbersB);Console.WriteLine("Unique numbers from both arrays:");uniqueNumbers.ForEach(Console.WriteLine);}

#pythondeflinq48():numbers_a= [0,2,4,5,6,8,9]numbers_b= [1,3,5,7,8]unique_numbers=set(numbers_a+numbers_b)print("Unique numbers from both arrays:")shared.printN(unique_numbers)

Output

Unique numbers from both arrays:0123456789

linq49: Union - 2

//c#staticvoidLinq49(){varproducts=GetProductList();varcustomers=GetCustomerList();varproductFirstChars=products.Select(p=>p.ProductName[0]);varcustomerFirstChars=customers.Select(c=>c.CompanyName[0]);varuniqueFirstChars=productFirstChars.Union(customerFirstChars);Console.WriteLine("Unique first letters from Product names and Customer names:");uniqueFirstChars.ForEach(Console.WriteLine);}

#pythondeflinq49():products=shared.getProductList()customers=shared.getCustomerList()product_first_chars= {p.ProductName[0]forpinproducts}customer_first_chars= {c.CompanyName[0]forcincustomers}unique_first_chars=product_first_chars.union(customer_first_chars)print("Unique first letters from Product names and Customer names:")shared.printS(unique_first_chars)

Output

Unique first letters from Product names and Customer names:GWRIPZLUCONFADTEJKSQHMBV

linq50: Intersect - 1

//c#staticvoidLinq50(){int[]numbersA={0,2,4,5,6,8,9};int[]numbersB={1,3,5,7,8};varcommonNumbers=numbersA.Intersect(numbersB);Console.WriteLine("Common numbers shared by both arrays:");commonNumbers.ForEach(Console.WriteLine);}

#pythondeflinq50():numbers_a= [0,2,4,5,6,8,9]numbers_b= [1,3,5,7,8]common_numbers=set(numbers_a).intersection((set(numbers_b)))print("Common numbers shared by both arrays:")shared.printN(common_numbers)

Output

Common numbers shared by both arrays:85

linq51: Intersect - 2

//c#staticvoidLinq51(){varproducts=GetProductList();varcustomers=GetCustomerList();varproductFirstChars=products.Select(p=>p.ProductName[0]);varcustomerFirstChars=customers.Select(c=>c.CompanyName[0]);varcommonFirstChars=productFirstChars.Intersect(customerFirstChars);Console.WriteLine("Common first letters from Product names and Customer names:");commonFirstChars.ForEach(Console.WriteLine);}

#pythondeflinq51():products=shared.getProductList()customers=shared.getCustomerList()product_first_chars= {p.ProductName[0]forpinproducts}customer_first_chars= {c.CompanyName[0]forcincustomers}unique_first_chars=product_first_chars.intersection(customer_first_chars)print("Common first letters from Product names and Customer names:")shared.printS(unique_first_chars)

Output

Common first letters from Product names and Customer names:ATCEQOWPFSGLVMKNIBR

linq52: Except - 1

//c#staticvoidLinq52(){int[]numbersA={0,2,4,5,6,8,9};int[]numbersB={1,3,5,7,8};varaOnlyNumbers=numbersA.Except(numbersB);Console.WriteLine("Numbers in first array but not second array:");aOnlyNumbers.ForEach(Console.WriteLine);}

#pythondeflinq52():numbers_a= [0,2,4,5,6,8,9]numbers_b= [1,3,5,7,8]a_only_numbers=set(numbers_a).difference((set(numbers_b)))print("Numbers in first array but not second array:")shared.printN(a_only_numbers)

Output

Numbers in first array but not second array:09246

linq53: Except - 2

//c#staticvoidLinq53(){varproducts=GetProductList();varcustomers=GetCustomerList();varproductFirstChars=products.Select(p=>p.ProductName[0]);varcustomerFirstChars=customers.Select(c=>c.CompanyName[0]);varproductOnlyFirstChars=productFirstChars.Except(customerFirstChars);Console.WriteLine("First letters from Product names, but not from Customer names:");productOnlyFirstChars.ForEach(Console.WriteLine);}

#pythondeflinq53():products=shared.getProductList()customers=shared.getCustomerList()product_first_chars= {p.ProductName[0]forpinproducts}customer_first_chars= {c.CompanyName[0]forcincustomers}unique_first_chars=product_first_chars.difference(customer_first_chars)print("First letters from Product names, but not from Customer names:")shared.printS(unique_first_chars)

Output

First letters from Product names, but not from Customer names:ZJU

LINQ - Conversion Operators

linq54: ToArray

//c#staticvoidLinq54(){varlist=newList<double>{1.7,2.3,1.9,4.1,2.9};vardoublesArray=list.OrderByDescending(d=>d).ToArray();Console.WriteLine("Every other double from highest to lowest:");for(vard=0;d<doublesArray.Length;d+=2){Console.WriteLine(doublesArray[d]);}}

#pythondeflinq54():doubles= [1.7,2.3,1.9,4.1,2.9]sorted_doubles=sorted(doubles,reverse=True)doubles_array=list(sorted_doubles)print("Every other double from highest to lowest:")d=0whiled<len(doubles_array):print(doubles_array[d])d+=2

Output

Every other double from highest to lowest:4.12.31.7

linq55: ToList

//c#staticvoidLinq55(){varwords=new[]{"cherry","apple","blueberry"};varwordList=words.OrderBy(x=>x).ToList();Console.WriteLine("The sorted word list:");wordList.ForEach(Console.WriteLine);}

#pythondeflinq55():words= ["cherry","apple","blueberry"]sorted_words=sorted(words)word_list=list(sorted_words)print("The sorted word list:")shared.printN(word_list)

Output

The sorted word list:appleblueberrycherry

linq56: ToDictionary

//c#staticvoidLinq56(){varscoreRecords=new[]{new{Name="Alice",Score=50},new{Name="Bob",Score=40},new{Name="Cathy",Score=45}};varscoreRecordsDict=scoreRecords.ToDictionary(sr=>sr.Name);Console.WriteLine("Bob's score: {0}",scoreRecordsDict["Bob"]);}

#pythondeflinq56():score_records= [{'Name':"Alice",'Score':50},                     {'Name':"Bob",'Score':40},                     {'Name':"Cathy",'Score':45}]score_records_dict= {s['Name']:s['Score']forsinscore_records}print("Bob's score: %s"%score_records_dict["Bob"])

Output

Bob's score: {Name: Bob, Score: 40}

linq57: OfType

//c#staticvoidLinq57(){varnumbers=newobject[]{null,1.0,"two",3,"four",5,"six",7.0};vardoubles=numbers.OfType<double>();Console.WriteLine("Numbers stored as doubles:");doubles.ForEach(Console.WriteLine);}

#pythondeflinq57():numbers= [None,1.0,"two",3,"four",5,"six",7.0]floats= (nforninnumbersifisinstance(n,float))print("Numbers stored as floats:")shared.printN(floats)

Output

Numbers stored as doubles:1.07.0

LINQ - Element Operators

linq58: First - Simple

//c#staticvoidLinq58(){varproducts=GetProductList();varproduct12=products.First(p=>p.ProductID==12);ObjectDumper.Write(product12);}