101 LINQ Samples: Aggregator Operators
Count - Simple
This sample uses Count to get the number of unique factors of 300.
- public void Linq73()
- {
- int[] factorsOf300 = { 2, 2, 3, 5, 5 };
-
- int uniqueFactors = factorsOf300.Distinct().Count();
-
- Console.WriteLine("There are {0} unique factors of 300.", uniqueFactors);
- }
Result
There are 3 unique factors of 300.
Count - Conditional
This sample uses Count to get the number of odd ints in the array.
- public void Linq74()
- {
- int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
-
- int oddNumbers = numbers.Count(n => n % 2 == 1);
-
- Console.WriteLine("There are {0} odd numbers in the list.", oddNumbers);
- }
Result
There are 5 odd numbers in the list.
Count - Nested
This sample uses Count to return a list of customers and how many orders each has.
- public void Linq76()
- {
- List<Customer> customers = GetCustomerList();
-
- var orderCounts =
- from c in customers
- select new { c.CustomerID, OrderCount = c.Orders.Count() };
-
- ObjectDumper.Write(orderCounts);
- }
Result
| CustomerID=ALFKI CustomerID=ANATR CustomerID=ANTON CustomerID=AROUT CustomerID=BERGS CustomerID=BLAUS CustomerID=BLONP CustomerID=BOLID CustomerID=BONAP CustomerID=BOTTM CustomerID=BSBEV CustomerID=CACTU CustomerID=CENTC CustomerID=CHOPS CustomerID=COMMI CustomerID=CONSH CustomerID=DRACD CustomerID=DUMON CustomerID=EASTC CustomerID=ERNSH CustomerID=FAMIA CustomerID=FISSA CustomerID=FOLIG CustomerID=FOLKO CustomerID=FRANK CustomerID=FRANR CustomerID=FRANS CustomerID=FURIB CustomerID=GALED CustomerID=GODOS CustomerID=GOURL CustomerID=GREAL CustomerID=GROSR CustomerID=HANAR CustomerID=HILAA CustomerID=HUNGC CustomerID=HUNGO CustomerID=ISLAT CustomerID=KOENE CustomerID=LACOR CustomerID=LAMAI CustomerID=LAUGB CustomerID=LAZYK CustomerID=LEHMS CustomerID=LETSS CustomerID=LILAS CustomerID=LINOD CustomerID=LONEP CustomerID=MAGAA CustomerID=MAISD CustomerID=MEREP CustomerID=MORGK CustomerID=NORTS CustomerID=OCEAN CustomerID=OLDWO CustomerID=OTTIK CustomerID=PARIS CustomerID=PERIC CustomerID=PICCO CustomerID=PRINI CustomerID=QUEDE CustomerID=QUEEN CustomerID=QUICK CustomerID=RANCH CustomerID=RATTC CustomerID=REGGC CustomerID=RICAR CustomerID=RICSU CustomerID=ROMEY CustomerID=SANTG CustomerID=SAVEA CustomerID=SEVES CustomerID=SIMOB CustomerID=SPECD CustomerID=SPLIR CustomerID=SUPRD CustomerID=THEBI CustomerID=THECR CustomerID=TOMSP CustomerID=TORTU CustomerID=TRADH CustomerID=TRAIH CustomerID=VAFFE CustomerID=VICTE CustomerID=VINET CustomerID=WANDK CustomerID=WARTH CustomerID=WELLI CustomerID=WHITC CustomerID=WILMK CustomerID=WOLZA |
OrderCount=6 OrderCount=4 OrderCount=7 OrderCount=13 OrderCount=18 OrderCount=7 OrderCount=11 OrderCount=3 OrderCount=17 OrderCount=14 OrderCount=10 OrderCount=6 OrderCount=1 OrderCount=8 OrderCount=5 OrderCount=3 OrderCount=6 OrderCount=4 OrderCount=8 OrderCount=30 OrderCount=7 OrderCount=0 OrderCount=5 OrderCount=19 OrderCount=15 OrderCount=3 OrderCount=6 OrderCount=8 OrderCount=5 OrderCount=10 OrderCount=9 OrderCount=11 OrderCount=2 OrderCount=14 OrderCount=18 OrderCount=5 OrderCount=19 OrderCount=10 OrderCount=14 OrderCount=4 OrderCount=14 OrderCount=3 OrderCount=2 OrderCount=15 OrderCount=4 OrderCount=14 OrderCount=12 OrderCount=8 OrderCount=10 OrderCount=7 OrderCount=13 OrderCount=5 OrderCount=3 OrderCount=5 OrderCount=10 OrderCount=9 OrderCount=0 OrderCount=6 OrderCount=10 OrderCount=6 OrderCount=9 OrderCount=13 OrderCount=28 OrderCount=5 OrderCount=18 OrderCount=12 OrderCount=11 OrderCount=10 OrderCount=5 OrderCount=6 OrderCount=31 OrderCount=9 OrderCount=7 OrderCount=4 OrderCount=9 OrderCount=12 OrderCount=4 OrderCount=3 OrderCount=5 OrderCount=10 OrderCount=7 OrderCount=3 OrderCount=11 OrderCount=10 OrderCount=4 OrderCount=10 OrderCount=15 OrderCount=9 OrderCount=14 OrderCount=8 OrderCount=7 |
Count - Grouped
This sample uses Count to return a list of categories and how many products each has.
- public void Linq77()
- {
- List<Product> products = GetProductList();
-
- var categoryCounts =
- from p in products
- group p by p.Category into g
- select new { Category = g.Key, ProductCount = g.Count() };
-
- ObjectDumper.Write(categoryCounts
- }
Result
| Category=Beverages Category=Condiments Category=Produce Category=Meat/Poultry Category=Seafood Category=Dairy Products Category=Confections Category=Grains/Cereals |
ProductCount=12 ProductCount=12 ProductCount=5 ProductCount=6 ProductCount=12 ProductCount=10 ProductCount=13 ProductCount=7 |
Sum - Simple
This sample uses Sum to get the total of the numbers in an array.
- public void Linq78()
- {
- int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
-
- double numSum = numbers.Sum();
-
- Console.WriteLine("The sum of the numbers is {0}.", numSum);
- }
Result
The sum of the numbers is 45.
Sum - Projection
This sample uses Sum to get the total number of characters of all words in the array.
- public void Linq79()
- {
- string[] words = { "cherry", "apple", "blueberry" };
-
- double totalChars = words.Sum(w => w.Length);
-
- Console.WriteLine("There are a total of {0} characters in these words.", totalChars);
- }
Result
There are a total of 20 characters in these words.
Sum - Grouped
This sample uses Sum to get the total units in stock for each product category.
- public void Linq80()
- {
- List<Product> products = GetProductList();
-
- var categories =
- from p in products
- group p by p.Category into g
- select new { Category = g.Key, TotalUnitsInStock = g.Sum(p => p.UnitsInStock) };
-
- ObjectDumper.Write(categories);
- }
Result
| Category=Beverages Category=Condiments Category=Produce Category=Meat/Poultry Category=Seafood Category=Dairy Products Category=Confections Category=Grains/Cereals |
TotalUnitsInStock=559 TotalUnitsInStock=507 TotalUnitsInStock=100 TotalUnitsInStock=165 TotalUnitsInStock=701 TotalUnitsInStock=393 TotalUnitsInStock=386 TotalUnitsInStock=308 |
Min - Simple
This sample uses Min to get the lowest number in an array.
- public void Linq81()
- {
- int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
-
- int minNum = numbers.Min();
-
- Console.WriteLine("The minimum number is {0}.", minNum);
- }
Result
The minimum number is 0.
Min - Projection
This sample uses Min to get the length of the shortest word in an array.
- public void Linq82()
- {
- string[] words = { "cherry", "apple", "blueberry" };
-
- int shortestWord = words.Min(w => w.Length);
-
- Console.WriteLine("The shortest word is {0} characters long.", shortestWord);
- }
Result
The shortest word is 5 characters long.
Min - Grouped
This sample uses Min to get the cheapest price among each category's products.
- public void Linq83()
- {
- List<Product> products = GetProductList();
-
- var categories =
- from p in products
- group p by p.Category into g
- select new { Category = g.Key, CheapestPrice = g.Min(p => p.UnitPrice) };
-
- ObjectDumper.Write(categories);
- }
Result
| Category=Beverages Category=Condiments Category=Produce Category=Meat/Poultry Category=Seafood Category=Dairy Products Category=Confections Category=Grains/Cereals |
CheapestPrice=4.5000 CheapestPrice=10.0000 CheapestPrice=10.0000 CheapestPrice=7.4500 CheapestPrice=6.0000 CheapestPrice=2.5000 CheapestPrice=9.2000 CheapestPrice=7.0000 |
Min - Elements
This sample uses Min to get the products with the cheapest price in each category.
- public void Linq84()
- {
- List<Product> products = GetProductList();
-
- var categories =
- from p in products
- group p by p.Category into g
- let minPrice = g.Min(p => p.UnitPrice)
- select new { Category = g.Key, CheapestProducts = g.Where(p => p.UnitPrice == minPrice) };
-
- ObjectDumper.Write(categories, 1);
- }
Result
Category=Beverages CheapestProducts=...
CheapestProducts: ProductID=24 ProductName=Guaraná Fantástica Category=Beverages UnitPrice=4.5000 UnitsInStock=20
Category=Condiments CheapestProducts=...
CheapestProducts: ProductID=3 ProductName=Aniseed Syrup Category=Condiments UnitPrice=10.0000 UnitsInStock=13
Category=Produce CheapestProducts=...
CheapestProducts: ProductID=74 ProductName=Longlife Tofu Category=Produce UnitPrice=10.0000 UnitsInStock=4
Category=Meat/Poultry CheapestProducts=...
CheapestProducts: ProductID=54 ProductName=Tourtière Category=Meat/Poultry UnitPrice=7.4500 UnitsInStock=21
Category=Seafood CheapestProducts=...
CheapestProducts: ProductID=13 ProductName=Konbu Category=Seafood UnitPrice=6.0000 UnitsInStock=24
Category=Dairy Products CheapestProducts=...
CheapestProducts: ProductID=33 ProductName=Geitost Category=Dairy Products UnitPrice=2.5000 UnitsInStock=112
Category=Confections CheapestProducts=...
CheapestProducts: ProductID=19 ProductName=Teatime Chocolate Biscuits Category=Confections UnitPrice=9.2000 UnitsInStock=25
Category=Grains/Cereals CheapestProducts=...
CheapestProducts: ProductID=52 ProductName=Filo Mix Category=Grains/Cereals UnitPrice=7.0000 UnitsInStock=38
Max - Simple
This sample uses Max to get the highest number in an array.
- public void Linq85()
- {
- int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
-
- int maxNum = numbers.Max();
-
- Console.WriteLine("The maximum number is {0}.", maxNum);
- }
Result
The maximum number is 9.
Max - Projection
This sample uses Max to get the length of the longest word in an array.
- public void Linq86()
- {
- string[] words = { "cherry", "apple", "blueberry" };
-
- int longestLength = words.Max(w => w.Length);
-
- Console.WriteLine("The longest word is {0} characters long.", longestLength);
- }
Result
The longest word is 9 characters long.
Max - Grouped
This sample uses Max to get the most expensive price among each category's products.
- public void Linq87()
- {
- List<Product> products = GetProductList();
-
- var categories =
- from p in products
- group p by p.Category into g
- select new { Category = g.Key, MostExpensivePrice = g.Max(p => p.UnitPrice) };
-
- ObjectDumper.Write(categories);
- }
Result
| Category=Beverages Category=Condiments Category=Produce Category=Meat/Poultry Category=Seafood Category=Dairy Products Category=Confections Category=Grains/Cereals |
MostExpensivePrice=263.5000 MostExpensivePrice=43.9000 MostExpensivePrice=53.0000 MostExpensivePrice=123.7900 MostExpensivePrice=62.5000 MostExpensivePrice=55.0000 MostExpensivePrice=81.0000 MostExpensivePrice=38.0000 |
Max - Elements
This sample uses Max to get the products with the most expensive price in each category.
- public void Linq88()
- {
- List<Product> products = GetProductList();
-
- var categories =
- from p in products
- group p by p.Category into g
- let maxPrice = g.Max(p => p.UnitPrice)
- select new { Category = g.Key, MostExpensiveProducts = g.Where(p => p.UnitPrice == maxPrice) };
-
- ObjectDumper.Write(categories, 1);
- }
Result
Category=Beverages MostExpensiveProducts=...
MostExpensiveProducts: ProductID=38 ProductName=Côte de Blaye Category=Beverages UnitPrice=263.5000 UnitsInStock=17
Category=Condiments MostExpensiveProducts=...
MostExpensiveProducts: ProductID=63 ProductName=Vegie-spread Category=Condiments UnitPrice=43.9000 UnitsInStock=24
Category=Produce MostExpensiveProducts=...
MostExpensiveProducts: ProductID=51 ProductName=Manjimup Dried Apples Category=Produce UnitPrice=53.0000 UnitsInStock=20
Category=Meat/Poultry MostExpensiveProducts=...
MostExpensiveProducts: ProductID=29 ProductName=Thüringer Rostbratwurst Category=Meat/Poultry UnitPrice=123.7900 UnitsInStock=0
Category=Seafood MostExpensiveProducts=...
MostExpensiveProducts: ProductID=18 ProductName=Carnarvon Tigers Category=Seafood UnitPrice=62.5000 UnitsInStock=42
Category=Dairy Products MostExpensiveProducts=...
MostExpensiveProducts: ProductID=59 ProductName=Raclette Courdavault Category=Dairy Products UnitPrice=55.0000 UnitsInStock=79
Category=Confections MostExpensiveProducts=...
MostExpensiveProducts: ProductID=20 ProductName=Sir Rodney's Marmalade Category=Confections UnitPrice=81.0000 UnitsInStock=40
Category=Grains/Cereals MostExpensiveProducts=...
MostExpensiveProducts: ProductID=56 ProductName=Gnocchi di nonna Alice Category=Grains/Cereals UnitPrice=38.0000 UnitsInStock=21
Average - Simple
This sample uses Average to get the average of all numbers in an array.
- public void Linq89()
- {
- int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };
-
- double averageNum = numbers.Average();
-
- Console.WriteLine("The average number is {0}.", averageNum);
- }
Result
The average number is 4.5.
Average - Projection
This sample uses Average to get the average length of the words in the array.
- public void Linq90()
- {
- string[] words = { "cherry", "apple", "blueberry" };
-
- double averageLength = words.Average(w => w.Length);
-
- Console.WriteLine("The average word length is {0} characters.", averageLength);
- }
Result
The average word length is 6.66666666666667 characters.
Average - Grouped
This sample uses Average to get the average price of each category's products.
- public void Linq91()
- {
- List<Product> products = GetProductList();
-
- var categories =
- from p in products
- group p by p.Category into g
- select new { Category = g.Key, AveragePrice = g.Average(p => p.UnitPrice) };
-
- ObjectDumper.Write(categories);
- }
Result
| Category=Beverages Category=Condiments Category=Produce Category=Meat/Poultry Category=Seafood Category=Dairy Products Category=Confections Category=Grains/Cereals |
AveragePrice=37.979166666666666666666666667 AveragePrice=23.0625 AveragePrice=32.3700 AveragePrice=54.006666666666666666666666667 AveragePrice=20.6825 AveragePrice=28.7300 AveragePrice=25.1600 AveragePrice=20.2500 |
Aggregate - Simple
This sample uses Aggregate to create a running product on the array that calculates the total product of all elements.
- public void Linq92()
- {
- double[] doubles = { 1.7, 2.3, 1.9, 4.1, 2.9 };
-
- double product = doubles.Aggregate((runningProduct, nextFactor) => runningProduct * nextFactor);
-
- Console.WriteLine("Total product of all numbers: {0}", product);
- }
Result
Total product of all numbers: 88.33081
Aggregate - Seed
This sample uses Aggregate to create a running account balance that subtracts each withdrawal from the initial balance of 100, as long as the balance never drops below 0
- public void Linq93()
- {
- double startBalance = 100.0;
-
- int[] attemptedWithdrawals = { 20, 10, 40, 50, 10, 70, 30 };
-
- double endBalance =
- attemptedWithdrawals.Aggregate(startBalance,
- (balance, nextWithdrawal) =>
- ((nextWithdrawal <= balance) ? (balance - nextWithdrawal) : balance));
-
- Console.WriteLine("Ending balance: {0}", endBalance);
- }
Result
Ending balance: 20