All but last element of Ruby array

Question

Let's say I have a Ruby array

a = [1, 2, 3, 4]

If I want all but the first item, I can write a.drop(1), which is great. If I want all but the last item, though, I can only think of this way

a[0..-2]   # or
a[0...-1]

but neither of these seem as clean as using drop. Any other built-in ways I'm missing?

Answer 1

I'm not saying this is any better...

>> a = t
=> [1, 2, 3, 4]
>> a.first a.size - 1
=> [1, 2, 3]

or a.take 3 or a.first 3

or do a.pop which will return the last and leave the array with everything before it

or make the computer work for its dinner: a.reverse.drop(1).reverse

or

>> class Array
>>   def clip n=1
>>     take size - n
>>   end
>> end
=> nil
>> a
=> [1, 2, 3, 4]
>> a.clip
=> [1, 2, 3]
>> a = a + a
=> [1, 2, 3, 4, 1, 2, 3, 4]
>> a.clip 2
=> [1, 2, 3, 4, 1, 2]

Answer 2

Have you tried "take"

a.take(3)

Answer 3

Out of curiosity, why don't you like a[0...-1]? You want to get a slice of the array, so the slice operator seems like the idiomatic choice.

But if you need to call this all over the place, you always have the option of adding a method with a more friendly name to the Array class, like DigitalRoss suggested. Perhaps like this:

class Array
    def drop_last
        self[0...-1]
    end
end

Answer 4

a[0...-1] seems like the best way. The array slicing syntax was created for exactly this purpose...

Alternatively, if you don't mind modifying the array in place, you could just call a.pop:

>> a = [1, 2, 3, 4]
>> a.pop
>> a
=> [1, 2, 3]