Here is a beginner-friendly list of the more common array methods you will need to keep in your toolbox as a Ruby developer. Arrays are one of the most common data structures in programming. Consisting of a container for a collection of data of any type. It holds an index that starts at "0" and Ruby has several built-in methods that will make your life easier working with arrays in your projects.

Creating an empty Array

empty_array = []

Creating an Array with data

fruits = ["Apple", "Orange", "Grapes"]

Accessing elements

Array#index - Using the index of sports array to return element

sports = ["baseball", "football", "basketball"]  
sports[1] #=> football (Reminder: Arrays are 0)
sports[0] #=> baseball (index of 0 == baseball) 

Returning an element by position

Array#first - This will return the first element in the array index

cars = ["Tesla", "Ford", "Kia"]
cars.first #=> Tesla

Array#last - This will return the last element in the array index

artists = ["Beyonce", "Madonna", "Drake"] 
artists.last #=> Drake 

Modifying elements

Array#push - Pushes an element at the end of the array

phones = ["iPhone", "Pixel"]
phones.push("Galaxy S") #=> phones = ["iPhone", "Pixel", "Galaxy S"]

Array#shovel - It uses the shovel symbol "<<" to add elements

phones = ["iPhone", "Pixel"]
phones << ("Galaxy S") #=> phones = ["iPhone", "Pixel", "Galaxy S"]

Array#unshift - Adds an element at the front of the array

phones = ["iPhone", "Pixel"]
phones.unshift("Galaxy S") #=> phones = ["Galaxy S", "iPhone", "Pixel"]

Array#insert - Adds an element at index position

phones = ["iPhone", "Pixel"]
phones.insert(1, "Galaxy S") #=> phones = ["iPhone", "Galaxy S", "Pixel"]

Removing elements

Array#pop - Removes an element at the end of array

sneakers = ["Nike", "Adidas", "Puma"]
sneakers.pop #=> sneakers = ["Nike", "Adidas"]

Array#shift - Removes an element at the front of the array

sneakers = ["Nike", "Adidas", "Puma"]
sneakers.shift #=> sneakers = ["Adidas", "Puma"]

Array#delete - Deletes an element by element name

sneakers = ["Nike", "Adidas", "Puma"]
sneakers.delete("Nike") #=> sneakers = ["Adidas", "Puma"]

Array#clear - Removes every element from the array

sneakers = ["Nike", "Adidas", "Puma"]
sneakers.clear #=> sneakers = []

Sorting elements

Array#sort - Sorts elements from least to greatest

numbers = [2, 1, 4, 3]
numbers.sort #=> numbers = [1, 2, 3, 4]

Array#reverse - Sorts elements from greatest to least

numbers = [2, 1, 4, 3]
numbers.reverse #=> numbers = [4, 3, 2, 1]

More useful array methods

Array#length - Returns the number of elements in the array

dogs = ["boxer", "pug", "bulldog", "bulldog"]
dogs.length #=> 4

Array#include? - Checks if an array includes an element

dogs = ["boxer", "pug", "bulldog", "bulldog"] 
dogs.include?("pug") #=> true (always returns a boolean)
dogs.include?("yorkie") #=> false 

Array#uniq - This removes duplicates from an array

dogs = ["boxer", "pug", "bulldog", "bulldog"] 
dogs.uniq #=> dogs = ["boxer", "pug", "bulldog"] 

Array#empty? - Checks if the array is empty

dogs = ["boxer", "pug", "bulldog", "bulldog"] 
cats = []
dogs.empty? #=> false (always returns a boolean)
cats.empty? #=> true 

Array#detect - Checks for the first instance of the element in the array

dogs = ["boxer", "pug", "bulldog", "bulldog"]
dogs.detect {|dog| dog == "bulldog"} #=> dogs = ["bulldog"]

Array#select - Checks for the multiple instances of the element

dogs = ["boxer", "pug", "bulldog", "bulldog"]
dogs.select {|dog| dog == "bulldog"} #=> dogs = ["bulldog", "bulldog"]

Array#each - Iterates through each element in array

names = ["Jack", "Jill"]
names.each {|name| puts "Hi, #{name}"}
#=> Hi, Jack 
#=> Hi, Jill

Practice

Get out into the wild and practice these methods on arrays in projects. These methods will be tools to solve plenty of Ruby programming problems. Arrays will come up in many languages as well so you could repurpose your knowledge of how to work with arrays. If this cheatsheet was helpful to you, please share this post with another developer.

Happy coding,

Terry Threatt