From: Tiago Nogueira <tjnogueira@...>
Date: 2009-01-15T20:42:27+09:00
Subject: Re: Returning a duplicate from an Array

Jimmy Kofler escreveu:
>> Pierre Pat wrote:
>> I'd do like this:
>> a.select{|x| a.index(x) != a.rindex(x)}.uniq
>>
>> Now, I wouldn't know which one is more efficient, but coding wise, I 
>> like that way :-)
>>     
>
> Here's yet another take on it:
>
> class Array
>    def dups
>       uniq.select{ |e| (self-[e]).size < self.size - 1 }
>    end
> end
>
> p [ 1, 1, 2, 2, 3, 3, 4, 5 ].dups   #=> [1, 2, 3]
>
> see: http://snippets.dzone.com/posts/show/4148
>
> Cheers,
>
> j.k.
>   
I Think that the way :

class Array
   def dups
      uniq.select{ |e| (self-[e]).size < self.size - 1 }
   end
end
p [ 1, 1, 2, 2, 3, 3, 4, 5 ].dups   #=> [1, 2, 3]


is more elegant!

tiago