public static void FilterOperatorsThatReturnBoolean()
{
var processor = new CarCsvProcessor("fuel.csv");
// Because these operators return a boolean they do not offer deferred execution.
var result = processor.List.Any( // Do any cars have a manufacturer named Ford?
c => c.Manufacturer.Equals("Ford")
);
var result2 = processor.List.All( // Do all cars have a manufacturer named Ford?
c => c.Manufacturer.Equals("Ford")
);
Console.WriteLine(result);
Console.WriteLine(result2);
}
public static void FilterBySpecificManufacturer()
{
var processor = new CarCsvProcessor("fuel.csv");
var query = processor.List.Where(c => c.Manufacturer.Equals("BMW") && c.Year.Equals(2016))
.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name);
foreach (var car in query.Take(10))
{
Console.WriteLine($"{car.Manufacturer} {car.Name} : {car.Combined}");
}
Console.WriteLine(query.First().Name); // Gets the first element of the sequence.
Console.WriteLine(query.FirstOrDefault().Name); // Gets the first element of the sequence or returns a default value for the type if the sequence is empty.
}
public static void FlattenData()
{
var processor = new CarCsvProcessor("fuel.csv");
var carNames = processor.List.Select(c => c.Name);
foreach (var name in carNames)
{
foreach (var character in name)
{
Console.WriteLine(character);
}
}
var carNameCharacters = processor.List.SelectMany(c => c.Name); // Iterates over nested sequences.
WriteEnumerable(carNameCharacters);
}
public static void ProjectingData()
{
var processor = new CarCsvProcessor("fuel.csv");
// You can project data from a large data source to a new anonymous class.
// This will allow you save space if you decide you don't want to use
// everything in the larger data set.
//
// For example...
var query = processor.List.Select(
c => new { c.Manufacturer, c.Name, c.Combined } // Converts data to an anonymous data type that just has 3 properties.
);
foreach (var car in query)
{
Console.WriteLine($"{car.Manufacturer} {car.Name} : {car.Combined}");
}
}
public static void JoinData()
{
var carProcessor = new CarCsvProcessor("fuel.csv");
var cars = carProcessor.List;
var manufacturers = Processor.ProcessManufacturersFromCsv("manufacturers.csv");
// Using query syntax
var query =
from car in cars
join manufacturer in manufacturers
on car.Manufacturer equals manufacturer.Name
orderby car.Combined descending, car.Name ascending
select new
{
manufacturer.Headquarters,
car.Name,
car.Combined
};
// Using method syntax
var method =
cars.Join(
inner: manufacturers,
outerKeySelector: c => c.Manufacturer, // Value that linq will join on.
innerKeySelector: m => m.Name, // Value that will match a car with a manufacturer.
resultSelector: (c, m) => new // Projects two objects that have been joined together and puts them into one.
{
m.Headquarters,
c.Name,
c.Combined
})
.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name);
WriteEnumerable(query.Select(c => c.Name));
WriteEnumerable(method.Select(c => c.Name));
}
public static void JoinOnMultipleObjects()
{
var carProcessor = new CarCsvProcessor("fuel.csv");
var cars = carProcessor.List;
var manufacturers = Processor.ProcessManufacturersFromCsv("manufacturers.csv");
// Using query syntax
var query =
from car in cars
join manufacturer in manufacturers
on new { car.Manufacturer, car.Year }
equals
new { Manufacturer = manufacturer.Name, manufacturer.Year } // The property names must be the same in each new object (Manufacturer & Year).
orderby car.Combined descending, car.Name ascending
select new
{
manufacturer.Headquarters,
car.Name,
car.Combined
};
// Using method syntax
var method =
cars.Join(
inner: manufacturers,
outerKeySelector: c => new { c.Manufacturer, c.Year }, // Value that linq will join on.
innerKeySelector: m => new { Manufacturer = m.Name, m.Year }, // Value that will match a car with a manufacturer.
resultSelector: (c, m) => new // Projects two objects that have been joined together and puts them into one.
{
m.Headquarters,
c.Name,
c.Combined
})
.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name);
}
