Ruby Forum Ruby > Remove first and last items from array

Hi,

I need to remove the first and last items in an array (which may have 1,
2 or more items so the resulting array after removal may be empty). I
came up with this:

a = [1,2,3,4,5]
2.times { a.pop; a.reverse! }

It works well, but do you think that there is a slightly less obscure
way!?

Cheers,

~ Mark

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Hi,

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

a = [1,2,3,4,5]
a.pop; a.shift;


Florian Gilcher

On Apr 8, 2008, at 6:30 PM, Mark Dodwell wrote:
> It works well, but do you think that there is a slightly less obscure
> way!?
>
> Cheers,
>
> ~ Mark
> -- 
> Posted via http://www.ruby-forum.com/.
>

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On Apr 8, 2008, at 18:30 , Mark Dodwell wrote:

> I need to remove the first and last items in an array (which may  
> have 1,
> 2 or more items so the resulting array after removal may be empty). I
> came up with this:
>
> a = [1,2,3,4,5]
> 2.times { a.pop; a.reverse! }

Hehe.

I think the natural idiom is a slice:

    a[1..-2]

It returns an array as long as a.length > 0.

-- fxn

On Apr 8, 11:30 am, Mark Dodwell <s...@mkdynamic.co.uk> wrote:
> way!?
>
> Cheers,
>
> ~ Mark
> --
> Posted viahttp://www.ruby-forum.com/.

a.shift
a.pop
?

Thanks, can't believe I didn't think of the 'shift' operation! Oh well, 
my crazy solution is quite funny I think...

~ Mark

In fact there _is_ slice :)
which takes the same args.
a.slice(1..-2)
and even a destructive
a.slice!(1..-2)
but for some reason my ruby really didn't like it... so never mind the
destructive part....

a.shift
a.pop

This reads a little better to me.
You don't want to collect the items at all right?

/Shawn

On 08.04.2008 18:56, Kyle Schmitt wrote:
>>
>>  I think the natural idiom is a slice:
>>
>>    a[1..-2]

Slice works pretty well - unless the array is small:

irb(main):004:0> a=(1..5).to_a
=> [1, 2, 3, 4, 5]
irb(main):005:0> a.slice! 1...-1
=> [2, 3, 4]
irb(main):006:0> a=[]
=> []
irb(main):007:0> a.slice! 1...-1
=> nil
irb(main):008:0> a
=> [nil]
irb(main):009:0> a=[1]
=> [1]
irb(main):010:0> a.slice! 1...-1
=> []
irb(main):011:0>
irb(main):012:0* a
=> [1]

Kind regards

  robert