[ruby-on-rails] Ruby: What is the easiest way to remove the first element from an array?

Lets say I have an array

[0, 132, 432, 342, 234]

What is the easiest way to get rid of the first element? (0)

You can use:

arr - [arr[0]]

or

arr - [arr.shift]

or simply

arr.shift(1)

This is pretty neat:

head, *tail = [1, 2, 3, 4, 5]
#==> head = 1, tail = [2, 3, 4, 5]

As written in the comments, there's an advantage of not mutating the original list.

[0, 132, 432, 342, 234][1..-1]
=> [132, 432, 342, 234]

So unlike shift or slice this returns the modified array (useful for one liners).

or a.delete_at 0

Use the shift method on array

>> x = [4,5,6]
=> [4, 5, 6]                                                            
>> x.shift 
=> 4
>> x                                                                    
=> [5, 6] 

If you want to remove n starting elements you can use x.shift(n)

You can use:

 a.delete(a[0])   
 a.delete_at 0

Both can work

You can use Array.delete_at(0) method which will delete first element.

 x = [2,3,4,11,0]
 x.delete_at(0) unless x.empty? # [3,4,11,0]

a = [0,1,2,3]

a.drop(1)
# => [1, 2, 3] 

a
# => [0,1,2,3]

and additionally:

[0,1,2,3].drop(2)
=> [2, 3]

[0,1,2,3].drop(3)
=> [3] 

You can use:

a.slice!(0)

slice! generalizes to any index or range.

Use shift method

array.shift(n) => Remove first n elements from array 
array.shift(1) => Remove first element

https://ruby-doc.org/core-2.2.0/Array.html#method-i-shift