From: "para.hsu@..." <para.hsu@...>
Date: 2005-10-16T20:31:55+09:00
Subject: Re: How to get non-unique elements from an array?

Hello!

How about this ?
(0...a.length-1).select{|i| a[i]==a[i+1]}.map{|i|a[i]}.uniq