Arrays in Ruby

Arrays are data structures that allow storing an ordered collection of elements of any type. They are a fundamental tool in Ruby for working with data sets.

Creation and access to elements: Link to heading

They can be created using square brackets and separating elements with commas.
The size of the array can be obtained with the size method.
Elements can be accessed by their index, starting with 0.
Negative indices can be used to access elements from the end of the array.

Examples: Link to heading

letters = ["q", "w", "e", "r", "t"]

letters.class # => Array

letters.size # => 5

letters[2] # => "e"

letters[-1] # => "t"

letters[100] # => nil

letters[-100] # => nil

lyrics.include? "q" # => true

lyrics.include? "b" # => false

Useful methods: Link to heading

first: Gets the first element of the array.
last: Gets the last element of the array.
count: Counts the number of elements that meet a condition.
map: Transforms each element of the array and returns a new array.
select: Filters the elements of the array and returns a new array with those that meet a condition.
min: Gets the minimum element of the array.
max: Gets the maximum element of the array.
sum: Sum all the elements of the array.

Examples: Link to heading

letters = ["q", "w", "e", "r", "t"]

letters.first # => "q"

letters.last # => "t"

letters.count { |x| x == "q" } # => 1

[1, 2, 3, 4, 5].count { |x| x.even? } # => 2

[1, 2, 3, 4, 5].map { |x| x \* 2 } # => [2, 4, 6, 8, 10]

[1, 2, 3, 4, 5].select { |x| xodd? } # => [1, 3, 5]

[1, 2, 3, 4, 5].min # => 1

[1, 2, 3, 4, 5].max # => 5

[1, 2, 3, 4, 5].sum # => 15

Handling different types of data: Link to heading

Arrays can store elements of any type, including other arrays.

Example: Link to heading

array = [4, 4.5, "string", :symbol, []]

array.map { |x| x.class } # => [Integer, Float, String, Symbol, Array]

Work with strings: Link to heading

Strings can be split into arrays using the split method.

Example: Link to heading

"hello world".split(" ") # => ["hello", "world"]

"hello world".split(" ").size # => 2

"hello world".split(" ").map { |x| x.upcase } # => ["HELLO", "WORLD"]

"hello world".split(" ").map { |x| x.upcase }.join("\n") # => "HELLO\nWORLD"

puts("hello world".split(" ").map { |x| x.upcase }.join("\n")) # HELLO WORLD

Sort arrays: Link to heading

They can be sorted using the sort method.

Example: Link to heading

letters = ["q", "w", "e", "r", "t"]

letters.sort # => ["e", "q", "r", "t", "w"]

sort_letters = letters.sort

letters # => ["q", "w", "e", "r", "t"]

sort_letters = letters.sort!

letters # => ["e", "q", "r", "t", "w"] # The original array is modified

Arrays are a powerful tool for working with data in Ruby. Their flexibility and simplicity make them a fundamental part of the language.