**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Data Structures: Arrays, Hashes, and Sets **Topic:** Working with arrays: creation, manipulation, and iteration ### Introduction In Ruby, arrays are a fundamental data structure that allows you to store and manipulate collections of values. In this topic, we will explore the creation, manipulation, and iteration of arrays, which is essential for any Ruby programmer. ### Creating Arrays Arrays in Ruby are created using the square bracket `[]` syntax. You can create an empty array using `[]`, or you can pass a list of values to create an array with initial values. ```ruby # Create an empty array my_array = [] puts my_array # => [] # Create an array with initial values my_array = [1, 2, 3, 4, 5] puts my_array # => [1, 2, 3, 4, 5] ``` You can also create an array using the `Array.new` method, which allows you to specify the initial values and the size of the array. ```ruby # Create an array with initial values and size my_array = Array.new(5, 0) puts my_array # => [0, 0, 0, 0, 0] ``` ### Manipulating Arrays Arrays in Ruby support various methods for manipulation, including: * `push`: adds one or more elements to the end of the array * `pop`: removes and returns the last element of the array * `shift`: removes and returns the first element of the array * `unshift`: adds one or more elements to the beginning of the array * `delete`: removes the first occurrence of a specified element * `delete_at`: removes the element at a specified index ```ruby # Create an array my_array = [1, 2, 3, 4, 5] # Add an element to the end of the array my_array.push(6) puts my_array # => [1, 2, 3, 4, 5, 6] # Remove the last element of the array my_array.pop puts my_array # => [1, 2, 3, 4] # Remove the first element of the array my_array.shift puts my_array # => [2, 3, 4] # Add an element to the beginning of the array my_array.unshift(0) puts my_array # => [0, 2, 3, 4] # Remove the first occurrence of the element 3 my_array.delete(3) puts my_array # => [0, 2, 4] # Remove the element at index 1 my_array.delete_at(1) puts my_array # => [0, 4] ``` ### Iterating over Arrays Arrays in Ruby support various methods for iteration, including: * `each`: calls a block for each element in the array * `each_index`: calls a block for each element in the array, along with its index * `map`: creates a new array with the results of applying a block to each element * `select`: creates a new array with the elements that satisfy a block * `reject`: creates a new array with the elements that do not satisfy a block ```ruby # Create an array my_array = [1, 2, 3, 4, 5] # Iterate over the array using each my_array.each do |element| puts element end # => 1 # => 2 # => 3 # => 4 # => 5 # Iterate over the array using each_index my_array.each_index do |index| puts "#{index}: #{my_array[index]}" end # => 0: 1 # => 1: 2 # => 2: 3 # => 3: 4 # => 4: 5 # Create a new array with the squares of the elements squares = my_array.map do |element| element ** 2 end puts squares # => [1, 4, 9, 16, 25] # Create a new array with the even elements even_elements = my_array.select do |element| element % 2 == 0 end puts even_elements # => [2, 4] # Create a new array with the odd elements odd_elements = my_array.reject do |element| element % 2 == 0 end puts odd_elements # => [1, 3, 5] ``` ### Conclusion In this topic, we have covered the creation, manipulation, and iteration of arrays in Ruby. We have also explored various methods for array manipulation, including `push`, `pop`, `shift`, `unshift`, `delete`, and `delete_at`. Additionally, we have discussed various methods for iteration, including `each`, `each_index`, `map`, `select`, and `reject`. With this knowledge, you should be able to work effectively with arrays in your Ruby programming projects. **Leave a comment or ask for help if you have any questions or need further clarification on any of the topics covered in this topic.** **Recommended Reading:** * [Ruby Documentation: Arrays](https://ruby-doc.org/core-3.1.0/doc/syntax/collections_rdoc.html#label-Arrays) * [Ruby Documentation: Array Methods](https://ruby-doc.org/core-3.1.0/doc/syntax/collections_rdoc.html#label-Array-Methods) **Practice Exercises:** * Create an array with 5 elements and manipulate it using the `push`, `pop`, `shift`, `unshift`, `delete`, and `delete_at` methods. * Iterate over an array using the `each`, `each_index`, `map`, `select`, and `reject` methods. * Create a new array with the squares of the elements in an array. * Create a new array with the even elements in an array. * Create a new array with the odd elements in an array.