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NullVoxPopuli
NullVoxPopuli

Reputation: 65183

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)

Upvotes: 322

Views: 264445

Answers (11)

vise
vise

Reputation: 13393

[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).

Upvotes: 140

scaryguy
scaryguy

Reputation: 7960

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]

Upvotes: 466

Avijit Majhi
Avijit Majhi

Reputation: 518

You can use:

arr - [arr[0]]

or

arr - [arr.shift]

or simply

arr.shift(1)

Upvotes: 6

Sanjay
Sanjay

Reputation: 382

You can use: 

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

Both can work

Upvotes: 2

Rahul Patel
Rahul Patel

Reputation: 1434

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

Upvotes: 18

lalit.sethi143
lalit.sethi143

Reputation: 146

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]

Upvotes: 6

hurikhan77
hurikhan77

Reputation: 5930

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.

Upvotes: 117

Sjoerd
Sjoerd

Reputation: 75679

"pop"ing the first element of an Array is called "shift" ("unshift" being the operation of adding one element in front of the array).

Upvotes: 316

zzzhc
zzzhc

Reputation: 395

or a.delete_at 0

Upvotes: 18

bragboy
bragboy

Reputation: 35572

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)

Upvotes: 339

Matthew Flaschen
Matthew Flaschen

Reputation: 285047

You can use:

a.slice!(0)

slice! generalizes to any index or range.

Upvotes: 15

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