Welcome! Today, we'll delve into Data Projection Techniques in C#! Data projection is akin to using a special light to make diamonds shine brighter amidst other gems, aiding their identification.
This lesson will illuminate the concept of data projection, its implementation using C#’s LINQ Select method, and how to integrate it with filtering. Let's forge ahead!
Data projection involves applying a function to a data stream's elements, resulting in a reshaped view. A common instance of data projection is selecting specific fields from datasets.
Data projection in C# employs the Select method from LINQ. You can define a reusable function using Func<int, int> to calculate each number's square, or directly embed the logic within Select for a single use. Here's an illustration using Func:
C#1using System; 2using System.Collections.Generic; 3using System.Linq; 4 5class Program 6{ 7 static void Main() 8 { 9 List<int> numbers = new List<int> { 1, 2, 3, 4, 5 }; // our data stream 10 11 Func<int, int> square = n => n * n; // function to get a number's square 12 13 // Select applies the square function to each number in the list 14 List<int> squaredNumbers = numbers.Select(square).ToList(); 15 16 Console.WriteLine(string.Join(", ", squaredNumbers)); // prints: 1, 4, 9, 16, 25 17 } 18}
Use Func for reusability in other code parts, or embed the logic directly inside Select if it’s a one-time operation.
For complex operations on data streams, C# employs lambda expressions (anonymous functions). Let's convert a list of sentences to lowercase:
C#1using System; 2using System.Collections.Generic; 3using System.Linq; 4 5class Program 6{ 7 static void Main() 8 { 9 List<string> sentences = new List<string> { "HELLO WORLD", "C# IS FUN", "I LIKE PROGRAMMING" }; // our data stream 10 11 // Select applies the lambda function to each sentence in the list 12 List<string> lowerSentences = sentences.Select(sentence => sentence.ToLower()).ToList(); 13 14 Console.WriteLine(string.Join(", ", lowerSentences)); // prints: hello world, c# is fun, i like programming 15 } 16}
C# seamlessly integrates projection and filtering. Now, let's lowercase sentences containing "C#" while dismissing others:
C#1using System; 2using System.Collections.Generic; 3using System.Linq; 4 5class Program 6{ 7 static void Main() 8 { 9 List<string> sentences = new List<string> { "HELLO WORLD", "C# IS FUN", "I LIKE PROGRAMMING" }; // our data stream 10 11 // Where selects sentences containing 'C#' 12 List<string> filteredSentences = sentences.Where(sentence => sentence.Contains("C#")).ToList(); 13 14 // Select applies the lambda function to each filtered sentence, converting it to lowercase 15 List<string> lowerFilteredSentences = filteredSentences.Select(sentence => sentence.ToLower()).ToList(); 16 17 Console.WriteLine(string.Join(", ", lowerFilteredSentences)); // prints: c# is fun 18 } 19}
By creating a DataProjector class, we'll encapsulate our projections for reusable, cleaner code:
C#1using System; 2using System.Collections.Generic; 3using System.Linq; 4 5class DataProjector<T> 6{ 7 private List<T> data; 8 9 public DataProjector(List<T> data) 10 { 11 this.data = data; 12 } 13 14 public List<TResult> Project<TResult>(Func<T, TResult> projectFunc) 15 { 16 return this.data.Select(projectFunc).ToList(); 17 } 18 19 public List<TResult> FilterAndProject<TResult>(Func<T, bool> filterFunc, Func<T, TResult> projectFunc) 20 { 21 List<T> filteredData = this.data.Where(filterFunc).ToList(); 22 return new DataProjector<T>(filteredData).Project(projectFunc); 23 } 24} 25 26class Program 27{ 28 static void Main() 29 { 30 List<string> sentences = new List<string> { "HELLO WORLD", "C# IS FUN", "I LIKE PROGRAMMING" }; // our data stream 31 32 // Creating a DataProjector object with our sentences 33 DataProjector<string> projector = new DataProjector<string>(sentences); 34 35 // Applying FilterAndProject to filter sentences containing 'C#' and converting them to lowercase 36 List<string> lowerFilteredSentencesList = projector.FilterAndProject( 37 sentence => sentence.Contains("C#"), 38 sentence => sentence.ToLower() 39 ); 40 41 Console.WriteLine(string.Join(", ", lowerFilteredSentencesList)); // prints: c# is fun 42 } 43}
Awesome! You've conquered Data Projection Techniques in C#! You've understood data projection, used Select, and integrated projection with filtering.
Remember our treasure box! This knowledge is your treasure box key, unlocking data manipulation aspects like raw data cleaning or web development data transformations. Now, revisit these concepts with practice exercises for mastery. Happy coding!