From: Nico Landgraf <nico@...>
Date: 2006-10-28T03:00:17+09:00
Subject: Re: how to get only the duplicatet items from an array

thanks, yes sir,
thats really what i'm looking for.
could you please post your fast way.

nico

Gavin Kistner wrote:
> From: Nico Landgraf [mailto:nico@nico-landgraf.de] 
>> is there a oneline to get only the duplicatet item from an array?
>>
>> i have an array like this
>> aTemp =  [1, 1, 2, 2, 3, 4]
>> and i want to know, which items are duplicatet.
> 
> There are faster ways to do this, but since you asked for a one-line:
> a = [1, 1, 2, 2, 3, 4]
> duplicates = a.delete_if{ |x| a.grep(x).length == 1 }.uniq
> #=> [1, 2]
>