Home » Ruby programming

Array.rotate() Method with Example in Ruby

Ruby Array.rotate() Method: Here, we are going to learn about the Array.rotate() method with examples in Ruby programming language.
Submitted by Hrithik Chandra Prasad, on January 26, 2020

Ruby Array.rotate() Method

In this article, we will study about Array.rotate() method. You all must be thinking the method must be doing something related to rotating certain elements. It is not as simple as it looks. Well, we will figure this out in the rest of our content. We will try to understand it with the help of syntax and demonstrating program codes.

Method description:

This method is a public instance method and defined for the Array class in Ruby’s library. This method works in a way that it rotates the content or objects present inside the Array instances. It rotates the Array elements in the way that the second element is considered to be first and the last object is considered to be the first element of the object of Array class. If you pass any negative integer inside the method then the rotation is done in the opposite direction. Array.rotate() is a non-destructive method where the changes created by this method would not impact the actual order of the Self Array instance and these changes are not permanent.

Syntax:

    Array_instance.rotate -> new_array
    or
    Array_instance.rotate(count) -> new_array

Argument(s) required:

This method does takes one argument and that argument decides from which index the rotation is going to be held.

Example 1:

=begin
  Ruby program to demonstrate rotate method
=end

# array declaration
Lang = ["C++","Java","Python","Html","Javascript","php","Ruby","Kotlin"]

puts "Array rotate implementation."
print Lang.rotate
puts ""

puts "The first element of the Array is: #{Lang[0]}"
puts "Array elements are:"
print Lang

Output

Array rotate implementation.
["Java", "Python", "Html", "Javascript", "php", "Ruby", "Kotlin", "C++"]
The first element of the Array is: C++
Array elements are:
["C++", "Java", "Python", "Html", "Javascript", "php", "Ruby", "Kotlin"]

Explanation:

In the above code, you can observe that we are rotating the contents of the Array class instance with the help of Array.rotate() method. You can observe that after rotating the contents, the first element is "Java" and the last element is "C++". Due to the fact that this method is a non-destructive method, it is not creating any impact on the actual arrangements of elements in the Array instance.

Example 2:

=begin
  Ruby program to demonstrate rotate method
=end

# array declaration
Table = [2,4,6,8,10,12,14,16,18,20]

puts "Array rotate implementation"
print Table.rotate(-2)
puts ""

puts "The first element of the Array is: #{Table.first}"
puts "Array elements are:"
print Table

Output

Array rotate implementation
[18, 20, 2, 4, 6, 8, 10, 12, 14, 16]
The first element of the Array is: 2
Array elements are:
[2, 4, 6, 8, 10, 12, 14, 16, 18, 20]

Explanation:

In the above code, you can observe that this method works on Integer Array as well and we are rotating the contents of Array class instance with the help of Array.rotate() method. Since we are passing a negative integer inside the method, the rotation is started from the back end side of the Array instance and the 2nd element from the last. You can observe that after rotating the contents, the first element is still 2 because this method is non-destructive and does not create any changes in the actual arrangements of contents in the Array instance.