Ruby: What is the easiest way to remove the first element from an array?
Ruby on-RailsRubyRuby on-Rails Problem Overview
Lets say I have an array
[0, 132, 432, 342, 234]
What is the easiest way to get rid of the first element? (0)
Ruby on-Rails Solutions
Solution 1 - Ruby on-Rails
Use .drop(1).
This has the benefit of returning a new Array with the first element removed, as opposed to using .shift, which returns the removed element, not the Array with the first element removed.
NOTE: It does not affect/mutate the original Array.
a = [0,1,2,3]
a.drop(1)
# => [1, 2, 3]
a
# => [0,1,2,3]
And, additionally, you can drop more than the first element:
[0,1,2,3].drop(2)
=> [2, 3]
[0,1,2,3].drop(3)
=> [3]
Solution 2 - Ruby on-Rails
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)
Solution 3 - Ruby on-Rails
"pop"ing the first element of an Array is called "shift" ("unshift" being the operation of adding one element in front of the array).
Solution 4 - Ruby on-Rails
[0, 132, 432, 342, 234][1..]
=> [132, 432, 342, 234]
So unlike shift or slice, this returns a new array, keeping the original array untouched (useful for one liners).
Solution 5 - Ruby on-Rails
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.
Solution 6 - Ruby on-Rails
or a.delete_at 0
Solution 7 - Ruby on-Rails
Use shift method
array.shift(n) => Remove first n elements from array
array.shift(1) => Remove first element
Solution 8 - Ruby on-Rails
Solution 9 - Ruby on-Rails
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]
Solution 10 - Ruby on-Rails
You can use:
arr - [arr[0]]
or
arr - [arr.shift]
or simply
arr.shift(1)
Solution 11 - Ruby on-Rails
You can use:
a.delete(a[0])
a.delete_at 0
Both can work